Finding Product ID

I was told that there are two kinds of Windows XP installation disc, one for VLK (volume License Key) and one for Retail/OEM. Each kind of Installation disc can only accept a Product ID from it's kind. So a legit Retail XP Product ID won't work on a VLK XP installation even when it's legit.

Why do I care all these? Because we got some development machines WITHOUT any installation disc. So first I need to use some freeware to retrieve the Product ID of each machine. But then I found out that not all the Product ID I retrieved worked on a XP VLK installation, and thus the above research result. The search result has not been totally proven, though.

And in case you didn't know, there are freewares out there that allows you to retrieve Product IDs:
- WindowsXP Product Key Viewer.exe
- SIW (System Information for Windows)

Both gave me consistent Product IDs.