Transfer/interchange Windows 7 Product Key

Guys
wondering if you've dug through this before. I do tech work for SOHO customers up to about 10 workstation size. I get a lot of dead machines. Some get rebuilt and flushed through Ebay. Some not worth doing. I harvest licenses, memory, etc.

Question: an OEM COA Product Key for Windows 7 that came pre-installed on a laptop: Can that Product Key be redeployed on another vendor's ware?
i.e. a dead HP notebook has a perfectly good Win 7 Product Key: Can't i redeploy that in upgrading a Dell Latitude to Windows 7?
NOTE: This is NOT a "CD" or media question. This is a question of Activation/Licensing/Legalities.

When I looked a this ages ago, my search had more to do with Server-based Key licensing vs retail/oem/other. That was a mess... I think at this point few use the server-based key licensing/refreshing scheme: it was HATED by the real world. Every time I have tried re-using a Windows 7 OEM/pre-install and/or retail key it has worked with no hitches.

This much I am 100% sure of: a "legit" Product Key stands on its own - legally it is not tied to hardware [not talking about embedded here...]. However, the Dell's and HP's of the world pay for these as a function of units shipped [estimates actually... I dealt with this in a past life] but the 'rights' conveyed convey with the Key not with media, and not with hard parts.

What say ye

 

Personally, after having had legit keys refused on a reinstall, and previously rejected (though legit) keys later accepted I've given up on trying to understand what is and what is not possible. Suck it and see I say.

 

It is a violation of the MS EULA to use the OEM COA/product key on a PC other than the original. However as you've pointed out yourself, you've already reused them without technical issue.