Which Windows Vista Edition are you?

If you are upgrading XP to Vista, make sure you backup and have the program "Windows Vista Upgrade Advisor"

Download Windows Vista Upgrade Advisor:
http://www.microsoft.com/downloads/details.aspx?FamilyId=42B5AC83-C24F-4863-A389-3FFC194924F8&displaylang=en

Be Sure to Backup with a removable media such as CD's, Floppy Disks or USB Flash Drives, External Hard Drivers.

Windows Vista Editions:

Windows Vista Home Basic
Windows Vista Home Premium
Windows Vista Business
Windows Vista Ultimate
Windows Vista Starter
Windows Vista Enterprise

These also include 64-bit.

Lastly, if you have XP and if it's Vista Capable, you don't need to use the upgrade advisor, you are allowed to use any, but you must download the drivers after upgrade.