Yeah i would say more so the x5200, because i think 1 extra mb of L2 cahce would make more of a difference then an extra 100mhz of clock speed. That's a pretty **** good o/c you got there though. Biostar TForce boards are good for O/Cing. Not to mention your chip itself is a great OCer.
Do you think with a 8800GT I could max out most games with smooth FPS? (with the exeption of crysis) ...My monitor tops out at 1600x1200, so I wouldn't need to play at any crazy resolutions.
with an 8800gt, most likely, but I'd get another 512mb of ram to make it 2 gigis and you should be cool. I can play crysis on medium settings decent with AA off, but my videocard isn't that good. If you aren't running crysis though then I'd say that yeah you're pc is fit to play the new games with an 8800gt.