There is an easy way
Jeremy and, actually, the preferred way.
Get your OS the way you want it. Install your stuff, settings etc.
Then activate by phone
Activate Windows 7 by Phone - Windows 7 Forums
(for both Seven and Vista)
Then maintian properly
To maintain your computer
10 Tips on How to Properly Maintain Your Computer
Steps that I did not notice on the guide include:
Running a scan disc before doing a defrag
Using Microsoft Security Essentials and Malwarebytes.
Making System Restore points, at least once a week
Makaing a system Image once a month (varies by user)
Not relying on your A/V common sense, should prevail. You know of many sites can cause a problem.
Do not use any reg cleaning or optimizing software.
Download and use Ccleaner about once every two months. Untick any registry entries.
If you follow these instructions, you will be trouble free for a long time to come.
Be sure to back up your hard drive about once a month (varies by user) and to keeep system restore points up to date.
Per your edit.
The upgrade version, if installed the way it shows in my tutorial, you are good to go with no problems, except maybe activation.
If you cannot activate with the key and you had Vista already installed, just explain to the technician when you try to activate. He will come on the phone if there is a problem activating.
You have 30 days to activate by phone. After 30 days, you will receive warnings and a gradual loss of functionality.