Best gfx card this system wont hold back.

You can use your current cpu,I wouldnt change it.And yes you can get a 8800 series dx10 cArd as well.I personally would wait til ati comes out with their dx10 first.And dont forget,two thinhs.One is youll certainly need a better power supply,Im guessing at least a quality 650 watter and second you may have install problems with the 8800 gtx board since it is verrry long

Depends on the games(demands of graphics) you play.If its oblivion then yes go for it(providing you dont mind spending the money)If its lessor demanding games then go for 7600gt or 1650 atito save a few bucks.With all eye candy the 1950 will give you best performance(for dx9)with maybe just a slight reduction in oblivion,rest is up to you

If I said I knew Id be lieing.No one knows how dx9 on a dx10 game will play.From what Ive read,theres less things availible,such as numbers of ai's,things you can move but nothing essential to the game,more or less just not as great as experince.There wont be many dx10 games out right away since most people have dx9 anyways and to date theres no lower/mid dx10 cards out and only nvids solution,besides all this youll need vista as well and even further at this point in time nvidia hasnt made any dx10 drivers for release yet About ocing..I dont think youll be able to oc your cpu,you may type in your mobo name and google it...sometimes you can BUT its highly risky.I wouldnt reccomend it,your 4200 should be ok for now