Gave this a shot and it definitely sped things up on start-up. I already had Aero disabled and had the system set up for performance, but there were a few more tricks in there I hadn't tried.
On boot up, however, my start-up bar had a message along the lines of "Unable to connect network drives". I'm not on a network, so that confused me a bit. I assume this is normal?
Youve probably just disabled a network option. Backtrack what you changed until you hit the right one.