Recently I came across sellers of Windows XP OEM on eBay.  One seller stated that in order to keep with Microsoft and eBay policies one piece of hardware chosen at random will be provided.
Please be aware, Microsoft Windows XP OEM version is only to be issued with a new PC.  It states this clearly on the packaging so anyone selling without a PC is breaking the law.
If you buy this particular software, you may have trouble activating with Microsoft online.  This is one of the reasons Microsoft did away with re-activation of OEM software online.
Please beware if you decide to purchase this software.
Happy bidding.