I used an upgrade option from W 7 Ultimate (32) to W7 Professional upgrade (64)
The result was not satisfactory. There existed a"old windows" which I could delete.
Some programs from my W 7 Ultimate still showed up and I could not delete these (requiring Administrator rights) even that I had these rights.
I formatted my drive and reinstalled with no problems. Even my serial for upgrade worked without problems for the clean install. I held in reserve Microsoft support at 1-800-936-5700 in case I would hav gotten the error 0xc004f061 for installing my upgrade in a clean install.