Experinced tech needs activation,upgrade advice

I have a customer that obtained several Hp\Compaq notebooks. The disk drives oln all of them have been erased clean and the Windows Vista Business Key stickers have been cut off. I intend to load a version of windows 7 on the notebooks but I don't know much about volume licsensing.
The Ms Windows site says that if the notebooks were loaded with a previous version of windows I needed a upgrade with some kind of volume licsense. The notebooks were loaded with Vista Business because I can see enough of the Product Id Sticker to tell so.
Any suggestions would be appreciated. Oh by the way I have 50 of these notebooks to fix.

If the COA stickers are incomplete, it's likely that the licenses have been voided.
If you load Vista onto one of them using the Default Key - please post an MGADiag report, and we'll see what we can learn.

To properly analyse and solve problems with Activation and Validation, we need to see a full copy of the report produced by the MGADiag tool
(download and save to desktop - http://go.microsoft.com/fwlink/?linkid=52012 )
Once saved, run the tool.
Click on the Continue button, which will produce the report.
To copy the report to your response, click on the Copy button in the tool (ignore any error messages at this point), and then paste (using either r-click/Paste, or Ctrl+V ) into your response.
- **in your own thread**, please

Please also state the Version and Edition of Windows quoted on your COA sticker (if you have one) on the case of your machine (or inside the battery compartment), but do NOT quote the Key on the sticker!
How to Tell


Note that Volume Licenses are all Upgrades - therefore, if the original licenses on these machines have been voided, you would first need to purchase appropriate license for each machine, and then upgrade to Volume license as required.
This could get expensive!
At the least, you would require an OEM System Builder license for each machine - presumably for Windows 7 Pro (or Win8 Pro!)
Alternatively, you could try contacting the manufacturer of these machines, and ordering Recovery disks for them - this would install the manufacturer's default install - but would only work if the SLIC table in the BIOS is still valid. (which is why I asked for the MGADiag report). They may have more to say about the COA Stickers as well.