Buying WindowsXP on eBay?


I’m looking for a legit copy of XP Pro SP2 on eBay, but I’m not sure what to get. There are so many of them, all legit copies with keys and such, but they don’t come in a box or anything - just the blue shrink-wrapped CD-case. In the description on most of them, it says “non-peripheral hardware included to comply with Microsoft OEM conditions”. This means it’s an OEM version, right? Plus, the OEM version doesn’t allow you to do an upgrade - it has to be a clean install…

Any tips?