Titanium: Once you back up everything that you don't intend to loose, it's just a matter of starting the format and then simply reinstalling the OS and then drivers and such. Unless you hit a snag along the way, which shouldn't be a direct result of the format, but an underlining and previously existing problem, you should be done with it in a few hours, give or take.
I've done it at least ten times by now, mostly for friends or family.
I'm more worried about drivers and such, is there much that isn't installed automatically with the OS?