You can do a search online about reinstalling Vista (clean install). There are even pages from Microsoft which explain how to do it. Here's one I found on Google:
http://windowshelp.microsoft.com/Windows/en-US/help/e77344fa-e978-464c-953e-eba44f0522671033.mspx One thing they mention is that you might need to have your computer boot from the CD/DVD drive. Make sure your computer is set up for that by going to the BIOS setup (when the computer starts) and change that option. You might need to find specific help for that.
If you are planning on doing a clean reinstall, remember that it deletes ALL the files in your computer, so make a backup of the files you want to keep before you start.
Good luck!
malu
