Hey like i said, It'* an Opinion. I didn't mean for it to be the words to live by here.
I would still prefer to get the 640 version over the 320 for the reason i would get the super charged bonnie over the N/A. It only a bit more so why not? Not for the fact that i'm running 2 22' windscreens but because it'* a powerhouse of a card. Why not use it to it'* full potential. I can't run SLI in my board cuz it only supports crossfire. But what if his board only has one PCIx16? you want him to buy a whole new board so he can get a second 320mb version later?
Some game engines out now like 512MB of VRAM. remember doom 3? how old is that game? i never got to play it on maxed out setting because of the warning about having a card with 512MB on it. Could i image paying XXX$ for a latest gen 8800 320 card that couldn't handle an old game like Doom 3 maxed out? i could have spent 80$ more and been assured of performance. Now once again, because i never tried it i don't know, maybe it will work on my 7900GS, but it seems to stick out in my head the most. and that wasn't DX10, I'm sure DX10 games are going to require a helluva lot more. So i'll hold onto my 7900 for now and when that day comes get the 640 when i'm sure it will be a helluva lot cheaper.
And what if you want to use higher than 1600*1200? And with Full AA and AF?
anything higher than 1680x1050 with AA and AF might start to benefit from the extra RAM and come close to justifying the extra cost of the 640MB, otherwise the 320MB should do the trick. If i bought that card knowing it was supposed to be a power house i would run 1680x1050 (native res) with maxed AA and AF because it should handle it. I spent the money. i wanna see it.
And thank you for the list of Direct X 10 games. I didn't know there where that many. The only ones i knew about were Crysis (Oh yes baby! isn't' here yet, can't wait. will it run on high settings with 320? It looks VERY realistic) and Starcraft 2 (isn't here yet, lookin forward to it) Hellgate: London ( isn't here yet but REALLY want it) and Bioshock (isn't here yet) which is why i said there were none.
And as for vista. until it has Far higher market penetration i will not even bother to worry about it. XP is rock solid on my rig and hell i still love Windows 2000. I had a guy offer me his Vista ultimate in trade for some computer work and i refused it. It took him about 2 days before he went back to windows XP.
But like i said. This is just MHO. If you don't like it or think its wrong disregard it. Somebody wanted some suggestions and i figured i would throw in my personal experience. Crossfire would have been nice to use with X1950s but once again money comes into play. Kids are expensive. At the time 7900GS was the best bang for the buck. And with an old ATI 9700 and 9600 I was happy with it.
Edited: forgot to activate flame shield!