Windows 7: Downgrade from 7 Ultimate to 7 Professional

Hi, Guys! I hope you can help me.

A few months ago, I needed to rebuild my system due to the death of a motherboard (the thing had actually warped), so I decided to have my computer guy upgrade me to Windows 7, as I was running Vista Home Premium at the time. We found a dealer selling inexpensive keys, so I decided to go ahead and get 7 Ultimate (x64 version).

Turns out the key I bought was a MSDN version, and was recently flagged, so I needed to buy a new one (idiot me forgot the old adage "if it's too good to be true, it is").

Anyway, due to financial conditions, the best I can afford is a copy of Windows 7 Professional (which has been checked and authenticated). Since I really don't use any of the Ultimate-only stuff, I won't miss it.

I've read several threads here about downgrading using a registry trick to make the computer think it's a repair rather than a fresh install, but I'd like to confirm that it still works. I also read that SP1 needs to be uninstalled before this can be done. Is that still the case, as well?

I have everything set up just the way I like it, and would rather not have to spend three days reinstalling everything...

Yes it just worked again yesterday for someone we helped here.

Change the registry keys shown to exactly as they appear here, then run a Repair Install with the Windows 7 Pro w/SP1 installer:

click on image to enlarge

If you really want to save money I'd buy the Home Premium Family 3 pack which is three licenses for the price of one for life. Most users don't need the extra features in Pro or Ultimate which are similar.

Well, I've already bought the 7 Pro disk, and I only have the one computer (though I do have a netbook with 7 Starter), so it's all good.

Thanks for the quick reply! I'm glad I won't have to uninstall SP1...