On my single solitary XP machine, it says "Windows XP Professional 2002 Version Service Pack 1". It doesn't say that I installed from a volume license or retail disk or MSDN disk (mine is from the Indiana University Volume License, actually).
In the normal place in the registry, HKLM>Software>Microsoft>Windows>Currentversion, there's a ProductID key, but no listing of the type of install that was done.
It's not in System Information, either.
I had to install a different Office to check it, but the MSDN disk I used gives a version number of 9.00.3281 (Premium SR 1). If I install SP2 or 3, I'm prompted for my install CD. If I put in, say, an OEM Office 2000 Premium SR1 or a Retail copy, I'm prompted again for the original installer files.
That's what I'm talking about. I run into it a lot. Often enough that it's a source of annoyance, anyway. In local common use there are retail versions of Office, OEM copies that came with PCs or local universities. Every once in awhile I run into someone who has snagged an MSDN/Microsoft Select or most annoying of all the copies that're MS-use-only (they'll only install if you enter "Microsoft" for your company name. I don't know where they're come from but I've run across them several times).