Video Card Questions, Selection Quesitons

ok first of all i was wondering, what the difference is between a 320mb (OC) video card and just a regular 320mb video card, if any, is it better, faster what?

I was reading on toms and they were doing a test between ATI and geforce and were rating the cards on various games. I kept seeing 320MB OC geforce out performing the 640mb geforce regular cards on almost all benchmarks. Now is that because the games were optimized for the lower end models or is the 320mb just better?

Also i have a selection question:
EVGA 8800 GT $249 512MB 256MB GDDR3 DX 10
----is the a big difference between these two??----
EVGA 8800 GTS $368 512MB 256MB GDDR3 DX 10

EVGA 8800 GTS $369 640MB 320MB GDDR3 DX 10 Money is no issue, please gimme an opinion i'd really appreciate it

The 320 OC will be the faster of the two. OC stands for OverClocked, which means that the core, shader and memory speeds have been increased.

The 320 OC will beat a regular 640 at lower resolutions, but as soon as you turn the res and texture settings up, the 640 will start to run away. More memory helps with higher textures and resolutions

Of the ones you listed, go with either the 8800GT 512 or the 8800GTS 512. They are based on a newer, less power hungry core that performs better than the older G80 GTS'.

To the OP,

The best bang for the buck card is the 8800 gt 512.

And according to Tom it also OC good.