I was browsing through Tom's Hardware when I stumbled upon this article
, them reviewing a 2GB GeForce GTX 285. Turns out it basically has the same performance across the board.
And so I'm left to wonder, when does more VRAM actually matter? Maybe RAGE will have an Ultra High setting like Doom 3 did that will maybe use lots of VRAM (well, for slightly clearer textures)?
In this case, you will get a big performance boost from 1GB to 2 GB only in a game using <1GB. by that time, the 1GB card is using system RAM (or maybe even page file, yikes!), which is quite a bit slower than graphics memory. the 2GB then, has the extra space to hold it in its own super fast memory.
of course, not even crysis will use more than 1GB, so unless it's dual monitors in nvidia 3D at 2560x1600 each with 16xQAA and maxed out, you won't need much more than 1GB. i'd say 768 is the most youd really need for now.