I've just been offered an 8800GT [I'm pretty sure it's the 512MB version, but could be 256] for £40 which I would be getting off my mate at uni when he goes home at Xmas.
Is it worth it upgrading from my 7900GS 256 which I run with a nice little OC when gaming of:
(Got the Akasa Vortexx Neo strapped on keeping everything cool, so temps don't go above 50 on load at this time of year)

or should I just wait till I can afford something like a 4850? The 7900 is capable in most Source games, but I have to play with most settings down in TF2, so I'm thinking Left4Dead would crawl with any detail. Would the GT do ok in Mafia II/GTAIV?
Is it worth it upgrading from my 7900GS 256 which I run with a nice little OC when gaming of:

(Got the Akasa Vortexx Neo strapped on keeping everything cool, so temps don't go above 50 on load at this time of year)

or should I just wait till I can afford something like a 4850? The 7900 is capable in most Source games, but I have to play with most settings down in TF2, so I'm thinking Left4Dead would crawl with any detail. Would the GT do ok in Mafia II/GTAIV?