My hard drive is dying, and as my pc is about 6 years old and struggling to keep up with games I don't think its worth upgrading (AMD Sempron 3000 Socket 939, MSI Mobo with built-in ATI Radeon Xpress200 GPU, 1Gb RAM, Barracuda 160Gb IDE HD, Phillips IDE DVD-Drive, crap old PSU) so I'm planning my first build. Taken apart numerous computers and added/changed hardware so have a good idea what I'm doing.
I know a couple of parts that I want but need help/advice on what other parts to use.
CPU - Intel Core 2 Quad Q6600
GPU - ATI HD4870 (one at first then once they're cheaper add a second for crossfire)
MOTHERBOARD - I have no idea on good motherboards for Xfire so any help would be appreciated.
RAM - Another thing I have no idea about, want 4Gb though.
HARD DRIVE - At least 500Gb
DVD-DRIVE - Considering a blue-ray/HD-DVD reader, these worth the money?
PSU - No idea how much power I'll need for all this, but want a bit extra for upgrades in the future (extra HD's, 2nd GPU etc)
I already have a case that I'll use.
With regards to price limit, I'm trying to get the best pc I can for under £1000. Won't be buying this for a few months as I need to save up for it.
Any help would be appreciated, thanks.

How do the AMD Phenoms compare to the Intel Core2Quads?
Wouldnt let me edit my post so had to make another

The top end Phenoms compare to the Q6600 or Q6700 at stock. Once you start overclocking, they are left in the dust.

CPU: Good Choice
GPU: Also a good choice. 2x 4850's will give you a much bigger bang for about the same price.
Motherboard: Don't know what you have available to you but you either want a P45 or X38/48 based Mb.
RAM: RAM is cheap. Any DDR2 4Gb (2x2Gb sticks) set will treat you fine.
Hard Drive: What ever is the most storage available to you for the least price.
DVD/RW: No! Unless you really want to watch blu-ray it is a waste of cash. A DVD/RW drive is more than enough.
PSU: Again, not sure what you have available to you. You want a high quality unit probably in the 700W - 800W range. Corsair, PCP&C, Enermax, Silverstone and a few others make good units. Go for the most +12V amperage you can get from a quality maker.

Thought the Phenoms weren't as good as the Intels, looks like I'll stick with my choice of CPU then.
I was considering 2x 4850's but thought once the price went down I could add a 2nd 4870 and it would be much more powerful.
Would i notice a huge difference in gaming on a 24 or 26 inch widescreen between 2x 4870's and 2x 4850's?
As for the RAM, HD and PSU i'll just keep an eye out for good deals.
Won't bother with a Blu-Ray Drive as I doubt I'm going to be watching any Blue-Ray films. Thanks for the help

Almost everything have already been written by outlw6669.
Just wanna add :
If you are already planning to buy 2 x HD4870, then do so from the begining.
Buy one now and buy the other next time.
Don't bother the 4850 if you can still afford the 4870.

1- For gaming rig E8400 is better than Q6600
2- MOBO: ASUS P5Q Deluxe LGA 775 Intel P45 Intel Motherboard
http://www.newegg.com/Product/Prod [...] 6813131297
3- RAM:
G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 is very good one
http://www.newegg.com/Product/Prod [...] 6820231166
And the best is: mushkin 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066
http://www.newegg.com/Product/Prod [...] 6820146785
4- Power Supply: PC Power & Cooling S75QB 750W ATX12V is a good choice
http://www.newegg.com/Product/Prod [...] 6817703009
5- Get one 4870 now and when prices drop get another

Thanks for the suggestions.
I was planning to get one 4870 now and then another when the prices drop, was just asking if there would be a big increase in performance between 2x 4850's and 2x 4870's on a 24inch screen

No huge difference, in crysis few fps
The rest of games really doesn't matter if you're getting 200 fps or 240
more than 30 fps no body can tell the difference

Might be worth me just getting 2x 4850's then as that would work out quite a bit cheaper. Thanks

Few more questions, which chipset is better P45, X38 or X48?
Also for a bit more, is it worth getting a motherboard with DDR3? Will this make it more futureproof?

The X48 chipset would be the best for you since you are looking at crossfire. The X48 chipset has 2 16x PCIe slots for full speed crossfire. They will also overclock very nicely since they support 1600MHz front side bus speeds and DDR2 1200.

The X48 = X38 just "officially validated" to run at 400Mhz FSB. Most X38 based Mb's are already supplier validated at 400Mhz and I have never heard of one that could not run it.

The P45 is the mainstream equivalent of the Xx8. It is manufactured in the newer 65nm process (90mn for the Xx8) so it runs cooler and is currently the best overclocker around. The downside to being a mainstream part is the lowered PCIe bandwidth. While the Xx8 will give you 2 PCIe 2.0 16x slots at full 16x, the P45 will only give you 2 at PCIe 8x speeds.

There is some debate as to weather or not this will really affect performance with the current offerings as PCIe 2.0 @ 8x offers the same bandwidth as PCIe 1 @ 16x. You can look at a few benches here and here if you want to educate yourself on it a little.

The first is Toms own article on the scaling of PCIe 2.0 with a 9800GX2 which, as it is still the most powerful card available, requires more bandwidth than the 4870. You can see that the vast majority of the time there is little to no change at 8x PCIe 2.0.

The second is the worst case of tweaktown's comparison of 4850 CrossFire on the X48 and P45 platforms. According to this review the PCIe 2.0 8x connection is significantly slowing performance. Crysis took the greatest hit in performance of all the games tested

It is hard for me to say what is correct with two contradictory benchmarks starring me in the face. I am leaning towards Tom's judgment just because they are a little more trusted. If Anandtech could do a comparison at some point we could put this to rest. I will say that a Xx8 based Mb would be a better choice for future upgradibility because of the full 16x lanes on bouth slots. Not that this really matters much unless you are going to CrossFire 2 4870x2's as Intel's new platform will be out bye the end of the year.

As for the RAM....
No, DDR3 is not worth it yet. In fact, you will not see any performance gains above DDR2 800. Ok, Ok, so you might see a 1-2% increase for spending more than 2x the cash. Unless you are running a server it is just a waste in my eyes. DDR2 800 will let you overclock to at least a 400Mhz FSB (3.6Ghz if you get the Q6600) so I see no problems with it.

CrossFire 4870 vs 4850 will give you around a 15-20% increase across the board. Either is faster than a GTX 280 90%+ of the time when the game has been profiled for CrossFire. As long as you have enough CPU horsepower behind it the only game I could see you still having problems with on a 24" would be Crysis.

@ kad,
I can 100% tell the difference between 30FPS and 60FPS (the fastest my LCD can refresh). Hell, when I was on a CRT I could still tell the difference between 60 and 100FPS. The higher the frame rate the more fluid and lifelike the game play.

Thanks a lot for the explanations.
Looks like I'll definatley go for a X48 motherboard, not bother with DDR3.
Still undecided on which GPU to go for, depends on prices and how much money I have when I buy all the parts

If you have the spare $$$ CF 4870 is a great choice. But, at least in the states, you can get nearly the same performance for $10 more than a single 4870 with CF 4850's.

4870 $309.99
2x 4850 $319.98 after MIR

Or, you could get a single 4850 now and CF it with a 4870x2 later. The x2 is supposed to have much better scaling in nearly every game than 4870 CF. It all depends on how much you want to spend and how much power you really need.

Ok my plans have changed a bit. I was planning to do a lot of gaming on this but have now decided that for the amount I game there isnt any point in Xfire so going to go with 1 4850 so wouldn't need to go for a X48 mobo.
I want to try and get the main parts of this and then add the others parts at a later date.
So what I need is CPU, Mobo, RAM & PSU and then I will add a newer HD and GPU later once I have more money
So the CPU is still going to be the Q6600 and still sticking with 4GB RAM.
Any suggestions on a good (cheap) mobo (needs SATA2, at least 2 PCI, 1 PCIe 16x)
Also how much power would I need for this?
Eventually it will be a Q6600 with ATI HD4850, 4GB RAM with 2 SATA HD's & 1 SATA DVDRW drive

EDIT: Forgot to say I live in UK so if anyone knows of any UK sites with good deals at the moment or just good prices for parts please post. Thanks

(why cant you edit posts? i keep forgetting things and end up having to make another reply)
Forgot to say I also have a Nvidia 7600GS to use for now until I buy the 4850 so don't need a built in GPU on the mobo (although if its Intel X3100 I dont mind having it as I use linux and Intel have some of the best drivers for their built in GPU's)