Well I personally have 8600gt which is a low profile but powerful enough to play on high settings many games, but if you want you can actually get a full size 9600gt which should run all your games extremely well enough.
There is also a low profile card of 9600gt and one of them is a low power too, it has basically the same kick as the full size except it only consumes 60w, but that's only if you are low on power supply.
And it also depends whether you have PCI-E and what's your processor and what your power supply is and another thing is how much you willing to spend :p
