Vista OEM hdd change

Hello,

I did a hdd change recently, performed a hdd clone, and since then I've been receiving notifications requesting me to activate Vista.

My Vista is OEM, on a non-Dell system. When attempting to reactivate, it won't accept my product key, and there is no option for phone activation. There is however, an option to 'contact Dell for assistance'. I did not receive a disc for Vista on purchase, it came preinstalled from the retailer that setup my machine.

As stated previously, this is a non-Dell system I've been using for close to 3 years with no issues. I do not see how a Dell OEM could exist on a non-Dell system. Can someone clarify on this?

Assuming my only option is to get a fresh copy of Windows, is it possible to upgrade from my current Vista OEM to a retail Windows 7 installation? I want to retain my data and configuration, and would prefer NOT to perform a fresh install.

Currently using Vista Ultimate SP2, OEM as specified previously, and 'supposedly' a Dell OEM.

Assuming I do upgrade, do I have to upgrade from Vista Ultimate>Windows 7 Ultimate, or can I upgrade to any one of the Windows 7 packages? Main priority here is data and configuration retention. I don't want to have to reinstall hundreds of my apps.

Thanks.