well, if anything, it would be preferable to get something with the best of both worlds, higher model number (more pixel pipelines) and more memory. I do believe that a 128MB 6600GT is better than your 256MB 6200 tho.
That's a debatable post, I have had BF2 top out at 730Mb of memory usage on full settings. Add to that the ram Windows uses and all background services and it adds up to more that 1Gb
Liminator said:
..... they say sum of the drivers don't work well.
nVidia drivers are no where near as buggy as ATi drivers (I'm seeing lots of complaints about the latest Cat 6.4's) so you should be fine with the latest WHQL release drivers on the nVidia site.