While on topic, I've been using Windows 7 backup for my backups for almost half a year now. I decided to reformat the other night and try to restore my Steam library from the Win7 backups, but guess what? I couldn't play any of the games. It always gave me the "Servers are too busy" blah and "Game is unavailable". After doing some research, I found a few things but still couldn't figure out WTH was up with my restore.
I verified game cache and tried to download any other updates available. No luck. So now I'm redownloading a few games.
I was also having some really bad performance issues with Source Engine games. But ever since the reformat, things have been running perfectly.
I guess I need to reformat more often eh?