Imaging Drives, need to change W7 product Key on OEM

Hi all...
My company purchased 5 new 6005 Pro HP MT.
They all came loaded with XP Pro but have the 7 pro media.
I loaded one up, updates, customized, etc.
I cloned the drive to another machine, and changed the product key for Office 2007 and reactivated it very quickly and easily.

Windows 7...on the other hand, isn't so easy. It is an OEM copy (legit 100% from HP)
When I go into properties of the Computer, it just says Windows is Activated and gives the Product ID. It's an OEM (obviously) Key.

I just want to be 100% legal...nothing fishy going on here.

I'm not spending 8 hours per box installing 7 and customizing it for the stores when all 5 boxes are identical. There has to be a registry key edit that I can do to enter the correct W7 product key and reactivate Windows.

TIA...

I found this...and tried the VB Script but it bombed.
Had to call MS, said it was an invalid Product Key.

Change Windows 7 Key | How to Change Windows 7 Product Key

Wow...so no better help or ideas huh?

i'm fairly sure, if you image it you will get the "Windows is not legal" message and then it will ask for a product key, no registry keys needed

As said, I bought 5 new PCs. All are installed with XP Pro OEM with the media/licenses for 7pro OEM.
All 5 obviously have different OEM Product Keys, unique to each machine.
If you image a drive it is stuck with the original OEM. I want them all to be 100% legal, I just don't want to load all 5 from scratch.
The first one I cloned worked fine...the second one said it was a non-genuine copy of 7 and I had to call MS.
All automated...of course.

I can change the Office 2007 Product key and reactivate it easy...worked like a charm.

I'm trying to do the right thing here, nothing shady.
I just don't want to load each PC up from scratch (installed with XP from HP) and spend 8 hours instead of 30 minutes.

You'll need to learn how to build the image and then use SysPrep to remove all the key info and such - so that when you put the image on the new computer and start it up, it asks you for user name, etc....