After microsoft update everything is gone

I upgraded my Windows Xp computer to Windows Vista Business.
After the upgrade (That took 6 hours) everything seemed fine. My desktop and
documenst etc was there as usual.

So i ran Microsoft Update and restarted the computer (another 30 minutes to
restart)

After that i logged in as usual on my user account, but then the problems
started.
All my settings are gone, my documents folder is empty, IE Favourites is
gone, desktop i Vista standard and the sidebar is not showing me the gadgets
i installed before i ran the update.

I have checked "users" folder and the original user is gone.

I've tried uninstalling the updates but it doesnt make any difference
(except that the computer only takes 3 min to restart instead of 30)

Computer has 3.7 in Experience index so i guess its good enough for Vista.

Where are my files and settings?