Microsoft has released a guide on how to tweak Vista for more performance.

Windows Vista and SP1 focus on delivering greater performance and
overall system responsiveness. By striking a balance between speed and
responsiveness, Windows Vista and SP1 deliver a level of performance
that has the greatest positive impact on the system’s usability.This
guide looks at the following areas of performance improvement:

• Making configuration changes that help a computer feel more responsive when you use it.
• Using hardware to boost the actual physical speed of a computer.
• Making configuration changes that help a computer to start faster.
• Making the computer more reliable may help increase performance.
• Monitoring performance occasionally so that you can stop problems before they get too big.

You can download it here.