I've never tried skype, but in my opinion MSN has the worst IM service. Messages constantly fail to get delivered and the client is bloated, specially with ads, but I stick with it since that's what most people use. Amongst my closest friends I use googletalk, it's the best IM service, years ahead of MSN, but I think it doesn't have webcam support in Linux, not sure if they fixed that already. What really surprised me most about googletalk, was when a time my ISP was having some trouble, googletalk would be the only thing that would work
