If I install an OEM version of Vista I purchased, can the OEM PRODUCT Key that came with the machine be used for activation?

Thanks all.Seems like a loaded question...

If the OEM install DVD / CDs match... technically yes.

Which terms if any, of the EULA might be violated I can't say, and you could also end up with a Microsoft piracy alert.

Often machines that come with an OEM preinstall of an operating system offer replacement disks for a fraction of the cost. I would make enquiries with the PC manufacturer first, I've heard of restore disks being offered for as little as $5.

If you want to use the key from one machine to install the OEM OS and use on another machine would be a definite breach of the agreement. I'll be more specific. I'm talking about using a legally purchased System Builder OEM disc with a Manufacturer OEM(Dell, HP, etc.) product key.

Thanks.The key is what gives Ownership...you can use any CD to install no matter where it came from...Yes, that sounds right. It is the product key that is sure proof of ownership.
Let's review what happened here. Was it something like the following?

Number 1.  A user somehow acquired a used computer made by one of the major manufacturers. It has a product key on the back panel that indicates it had a Vista installation .

Number 2.  There was no installation DVD in the transaction of the computer to the new owner.

Number 3. the new owner buys a  copy of the DVD used to install the OS on this brand of computer. He uses the given product key and everything is okay.

WAIT! What did he say?
Purchased System Builder OEM disc.

Nor sure. You may have to call Microsoft.

Edit: Here is a link. http://oem.microsoft.com/
Search for 'System Builder'
Results vary by region.

 
Man, I really hate having to call somebody. 

The user/owner of the machine is someone I know who needs a fresh install, however, as Geek-9pm guessed, does not have the disc that came with the pre-owned machine. The System Builder copy is actually mine. To me, as long as I use their product key, not mine, and the versions are the same, then this is "morally" correct. It was just a matter of --technically can this be done. Microsoft has been far from simple, when it comes to product KEYS and the 47 versions of each Windows release.The phone call ...if needed at all should be no more than 2-3 minutes...
Go ahead with the install you may not even need it.....so it works, couldn't use online activation, had to use the automated phone system thingy. No big deal.