Well, there have been a few threads recently about 3DMark scores and 4850's paired with older systems. I just wanted to add my data to the discussion. The system is the one in my sig and for specifics you can check my configuration in my profile. The important stuff is:

FX-60 (AMD Athlon X2) @ 2.81GHz
2GB DDR1 400MHz
Asus 4850 @ Stock

Scores:

3DMark06:

Total: 9863
SM2.0: 4300
SM3.0: 5120
CPU: 2055


3DMark Vantage:

P5417
GPU 6011
CPU 4178

I can also run the feature tests for either, but I didn't record the scores.

Not all too impressive. I'll have to try some games next (probably Oblivion and Assassins Creed) but I have a strong feeling that these benches are way more CPU bound than all of my games.

how much do you think the 4850 is going to score with a intel pentium d 820?

Well, sadly 3DMark06 is a little too reliant on processor speed. I would even dare suggest something like 3DMark05 or even lower versions of 3DMark as it would easily show GPU power.

Even better is benchmarks included in games such as Call of Juarez, Crysis, etc...

Wow! I just tried out Oblivion (with all kinds of visual mods, of course) and it ran flawlessly with 8xAA/16xAF and everything else in CCC and ingame maxed. My old 2900 could barely do 2x and it had a lot of trouble in grass. I've only tried one game and I already feel like this card was worth it. I can't wait to try DX10 with Assassins Creed!

This is the problem with a lot of reviews and benchmarks, I personally don't think they should use anything other than a selection of games. Sure a lot of people run 3DMark but again this is only me but i just do it to have an additional control point if you like, so i can check the system upgrades that i make for performance increases.
There was a link (sorry i didn't save it ) on the forum a few days ago that showed a huge increase in games when changing a 3 series card for a 4 series on a 3GHZ AMD chip I think.
And here you are with something similar i think and according to 3DMark its not that good. Kinda goes to prove the point really.
Mactronix

Yeah, at my resolution the 2900 was plenty except when I enabled AA. With the 4850 it's 8x all the way. Just tried out Assassins Creed and it ran fine on max DX10, though that isn't really a surprise.