User blog:Cheesingfrogs/Steam or Games for Windows Live for PC Gaming?

PC Gamers, which do you use, Games for windows live, or steam? With steam you download your games and play with other "Steamers", and with GFWL you buy the disk and play that service. Which is better, in your opinion? And if I bought MW2, or a different CoD on a disk, so I would be playing GFWL, could I play with people on the steam service?

Thanks :D