Hi Don,
welcome to the forum.. Vista already comes with a couple of cleaning and maintenance utilitys.. These can be found in the start menu with 'Disk Clean' dealing with old web pages and folders as well as a Defragmentation utility for your hard drive. Using both on a regular basis will go a long way to keeping your os running nice and smooth.
I also use a utility called Ccleaner which is free and can be downloaded here:
Download CCleaner 2.08.588 - FileHippo.com
This is like an advanced version of the disk clean utility and will also clean the registry too..
If you would like more reading on the subject and also have an excellent guide then try the 'Tweakguides' for vista which again is free and available from here:
Link...