Well here is what I have discovered regarding VRAM. I run all my games @ 1680 x 1050. Usually w/ 4x AA and 16AF.
Most modern games, and vantage / unigine use somewhere between 300MB-650MB VRAM depending on the game at this resolution and AF / AA settings. So, a card 1GB of VRAM is called for in gaming at this resolution sometimes =)
Its no longer the days of, oh you only need 512MB if your playing and lower - medium resolution with little AA.
This is on a nvidia GTS250
I am getting a GTX 460 this week as replacement, if the VRAM usage changes due to architecture I will let you know=)