Need Help Please!! Problems with upgrading

I am upgrading from vista home premium to ultimate and i have downloaded vista ultimate x86 which should be compatible with my 32bit OS. I ran the installation/upgrade and it was fine until at one point it gives an error message saying:

“Windows could not prepare the computer to boot into the next phase of installation. To install Windows, restart the installation.”

I restarted the computer and ran the installation again but no change...any ideas?

I think it doesnt like some program your using, your going to have to clean install.

Humm, let's try this.
Control panel/Programs, then turn windows features on/off
Turn off:
NET 3.0 XPS viewer
Windows DFS Replication Service
Remote Diff Compression

Try upgrade then if it works turn back on the above features.

Sid.