Windows 7: Can't Activate Re-Installation of Win7

I bought Windows 7 Upgrade when it came out, and upgraded an XP laptop. Worked fine. The disk got corrupted, though, and I had to do a complete, clean install on a re-formatted harddrive. So my Windows 7 upgrade doesn't think it's an upgrade. I tried to do the online activation -- didn't work. I tried to do a phone activation -- didn't work. Talked to MS customer service. They said I have to install/activate Xp or something first, then re-install Windows 7 upgrade. The problem is that this laptop didn't come with any disks, and I don't have any way to do that. So they said to "borrow" a copy of XP/Vista from someone, install that, then re-install Windows 7 upgrade.
I just spent two full days installing Windows 7, updates, programs, data, etc. I sure hate to have to start all over again. Is there any other way to make this work?
Thanx/Jerry

Yes, theres a full scale tut on how to clean install with an upgrade disk. Esp. note the registry workaround method in Option 3.

Clean Install with a Upgrade Windows 7 Version

Opt 3 worked perfectly!!! Thanx so much. (I had actually read that tutorial before, but after my conversations with Microsoft's No-Customer-Support person, it didn't dawn on me to ignore what they said and go back to the tutorial. That almost cost me days of additional grief.)
I'm a happy camper now. Cheers/Jerry