I am having a similar problem as another user has explained on the forum with this code. I upgraded to Windows Vista Home Basic from Windows 2000 Professional (OEM) because the 2000 product was becoming unusable. When I try to activate I am getting the code 0xC004F061, the Software Licensing System has determined that this specified product key can only be used for upgrading, not for clean installations.
When I did the install it forced me to do a clean install and would not let me enter the product key. After hours and hours of work I finally have it installed, found drivers or workarounds, got my wireless connection connected again and it is operating much better than my old operating system, albeit quite slowly. The software is not offering me the option of a phone number to activate the software and I can't find one on the Microsoft site.
I don't understand why it cannot validate since both sets of software were legally purchased and there is a windows.old folder that has the info from the old operating system on the computer.
Re-installing Windows 2000 (to get validation) is not an acceptable alternative. There are 4 service packs to download and then I will probably run into the same problem again of Vista not allowing the upgrade.
My hardware is older but meets the requirements and I should be able to do the upgrade. Any assistance would be greatly appreciated.

Hi,
The upgrade has to be started from within a qualifying product. Win2000 cannot be upgraded to Vista Home Premium, only Business or Ultimate, which is why you had to use the custom install and could not enter a product key. Insert your Vista DVD, start an in-place upgrade to the current installation and you should be able to enter the Product Key now. You will have to complete the reinstall, then you should be able to activate.
Best of Luck,
Rick Rogers, aka "Nutcase" - Microsoft MVP mvp.support.microsoft.com/ Windows help - rickrogers.org My thoughts rick-mvp.blogspot.com
"Paul"