Advise on graphics card upgrade

It's time to upgrade my old graphics card but I can't decide what new one to buy.

My current system:

Intel Pentium Dual-Core E6300 (2,8Ghz)
4GB Corsair Twinx Memory
MSI N9600GT 512MB

Games I play the most at the moment are:

Battlefield Bad Company 2
EVE Online
Mass Effect 2
Sacred 2
UT 3

I have been looking at replacing it with the following cards:

Nvidia GTX260
Nvidia GTX275
Ati Radeon 5770
Ati Radeon 5830

I just wonder if putting something like the 5830 or GTX275 has any use or will the games be bottlenecked by the CPU.