which card should i get?

I found a good on this cards

8800 GTS 320MB $88 SHIPED

8800 GTS 640MB $128 SHIPED

so my question which one is better? is the $40 worth getting $640mb verision?

I found a good on this cards

8800 GTS 320MB $88 SHIPED

8800 GTS 640MB $128 SHIPED

so my question which one is better? is the $40 worth getting $640mb verision?

Metroid2006

the 40 dollars is definitely worth it ... the 320 is an ok card for lower resolutions but if you plan on playing at 1600x1000 or higher (aka a 21 inch monitor or better) you will need the 640 mb.