It will be fine, I run a 1GB GTX460 on dual screens, one for gaming, one for everything else whilst gaming (web browser, combat tracker for the game I play, messenger, steam chat window, stuff like that)
Believe me, it will be fine, my 256mb integrated on my old PC world laptop runs two screens easily, I use the inbuilt for games, the other for skype and music. Games is COD 1 but I haven't gamed for a long time now as I am not a gamer! Should be absolutely fine though, the only time you could possibly encounter problems is if you game on both of them. Even then, a lot of games will be fine but some just won't work. Especially if you have a high res.