now my question is i have a compaq it has an amd x2 7550 now it's not the best but it's better then my old x2 4800 i want to play games so what video card won't be bottlenecked by the cpu i installed a 500 power supply with a total of 30amps on the 12v rail
A HD4850/GTS250/9800GTX/GTX+ will be fine up to 16x10 with game settings at high.
If you want to push harder or play very demanding games look at the 1Gb HD4870 or GTX260.
Anything more will, possibly, cause stability problems by drawing too much power.
That depends on the resolution and type of game you play.
AT 1280x1024 or around that leval, go for the HD4850 class of card, at 16x10 or higher, the HD4870/GTX260 will be better.
The 'bottleneck' will also depend on game settings: The higher the settings, the less 'bottleneck' there will be.