is asus p5e http://www.overclockers.co.uk/show [...] =MB-249-AS
good for CF 2X4870 ?

I mean will I have better performance with it against p45 chipset in crossfire?

Can anyone recommend this motherboard? Is it good? what are its disadvantages? Is there any better option ?

Yes it's good.

Yes it will have better performance than P45. Read this: http://www.tweaktown.com/articles/ [...] index.html

Personally I prefer Gigabyte to Asus these days. Also, X48 is replacing X38. Here's a better option:
http://www.scan.co.uk/Search.aspx?q=GA-X48-DS4

How much difference in performance do x35 have with x48? Is it notiecable? I cant really pay any extra £20 so is there anything better in x35 chipsets?

You could get the GA-EX38-DS4 or the aBit IX38 QuadGT. Both are 6 pounds less than that P5E. Or the P5E, if you prefer Asus. As long as you have an X38 you're fine.
http://www.overclockers.co.uk/show [...] =MB-137-GI
http://www.overclockers.co.uk/show [...] =MB-138-AB

Between X38 and X48 - no worries, there's no difference in GPU speed.

What kind of PSU do you have?

still unsure about motherboard. which one to choose?
Gigabyte GA-EX38-DS4 http://www.overclockers.co.uk/showproduct....rodid=MB-137-GI
Abit IX38 QuadGT http://www.overclockers.co.uk/showproduct....rodid=MB-138-AB
P5E http://www.overclockers.co.uk/showproduct....rodid=MB-249-AS

Go with the GA-EX38-DS4. It doesn't really matter, all 3 are good.

Dump the WD5000AAKS and get a WD6400AAKS or WD7500AAKS instead. The 640/750 GB versions have a new technology called PMR which makes them a lot faster.

I have a Scythe Ninja myself. Same price as the Scythe Mugen, but it's better. That is, the Ninja with a single fan usually matches the Mugen with two fans.
http://www.scan.co.uk/Product.aspx?WebProductId=296802