I use Pidgin, and I think it's the best IM software there is for linux. Of course, except for it I know only aMSN, emesene and Kopete. Pidgin is, I think, cleaner and more stable.
But there is a minor problem - I can't use my webcam with it. It's an integrated webcam. My notebook is a Dell Vostro 1400. Is there some plugin, or something, that may allow me to use my webcam? I use a MSN account.