Soleron on 05 January 2013
It's not really a relevant spec. Every card you can find >$100 (and I wouldn't recommend going under that for gaming) will have enough memory to store the game textures.
Here's a chart of graphics card relative performance: http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.html
The rest of that article has some reasonable recommendations for price and desired resolution/settings.
