How to “upgrade” from VS 2010 Ultimate trial to Professional

Question

I have Visual Studio 2010 Ultimate Trial installed, which is about to expire. I also have a retail box with Visual Studio 2010 Professional. So I thought changing my trial to the full version would be as simple as entering the key, but no, it tells me that the key is invalid. OK, so I ran the setup from the Professional DVD. It accepted the key and appeared to install just fine (didn't mention anything about it already being installed). At the end it said that setup was completed successfully. When I ran it, however, it was still Ultimate Trial and still expiring in 3 days. Has anyone successfully done this without uninstalling and reinstalling, which would take me half a day?

Answer 1

I finally uninstalled Ultimate and (to my great surprise) I still had a shortcut to "Visual Studio 2010". When I opened it it ran Pro, no problem, as if nothing happened. So basically the following path works just fine:

1. Install Ultimate
2. Install Pro (in the same directory!)
3. Uninstall Ultimate