As its name implies, Stardock’s TweakVista lets you alter and fine-tune Vista in countless ways. A blessedly simple and well-designed interface makes tweaking easy.
You can see which programs run at startup and how much RAM each active program is currently using, as well as the Vista security parameters that are in force. A particularly useful feature is the Services module. This enables you to switch various Vista services on or off, depending on how you want to use your computer.
Another utility in TweakVista’s tool box will customise the way UAC works. For a free program, this one is hard to beat. A full version, priced at around $20, offers benchmarking, analysis of system startup and shutdown, and similar features. But for the basics, the free version suffices.