How to backup data of all users?

I had a lot of different versions installed. I uninstalled them all and then re-installed 3.5 SP1 only. Then I downloaded all the recommended hotfixes and service packs from windows update. Now I have the following installed.

.Net 2.0 SP2

.Net 3.0 SP2

.Net 3.5 SP1

Didn’t seem to make any difference.