Changing Operating System w/o losing data?

I know how to downgrade OS and I want to downgrade since Vista sucks

Anyway i want to downgrade but I don't want to lose data

How can i not lose data when i downgrade the OS?Changing Operating System w/o losing data?
Backup, or copy all your data files onto a CD/DVD or external hard drive or flash drive!Changing Operating System w/o losing data?
Move the information to a new partition on your hard drive. Then when you change the OS, just format the partition without your information and install.Changing Operating System w/o losing data?
Here's a cool way to do just that:

1. Move everything you want to save into a folder on the c:\ root eg. c:\saved files

2. Download an Ubuntu Linux live CD/install CD. This will allow you to boot to Linux from the CD. Once loaded load your hard drive and delete everything on the drive except c:\saved files. Reboot

3. Load the Windows XP cd. It might tell you that there is already a version of windows installed but continue anyways. DO NOT REFORMAT. You should be able to install on the existing partition.

4. Once done you'll be running XP and c:\savefiles will still be there.