Systerac Tools for Vista
If you're looking for an everything-including-the-kitchen-sink performance tool for Vista, here's the one to get. You'll find a memory optimizer, disk doctor, Registry backup, Registry optimizer, shutdown scheduler, Internet booster, Startup manager--and that's just the beginning. There are plenty of other tools as well, including a file shredder, and a nifty tool that displays a complete list of all your hardware.
That's the good news. Now the bad news: there are plenty of nag screens here that pop up whenever you want to use one of the program's features. The trial is good for only 14 days, but even during those 14 days, you'll be nagged constantly. If you can put up with that, however, you'll find this a useful program.
Note: This link takes you to the vendor's site, where you can download the latest version of the software.