Jafo, from what I read, a lot of legit OEM software/hardware are NOT supported by the manufacturers. I guess that's why the manufacturers sell it cheap to the dealers, because they avoid the headache of customer support for these. I went through a few web sites and a lot of the manufacturer clearly say that they don't support OEM products "please contact your dealer for support" is basically what they say.
And again, one can only buy OEM software with either a new computer or in confunction with the provision of a non-peripheral hardware upgrade for an existing computer (so basically it means any hardware that's not a peripheral). These are Microsoft rules, as they can be read in the paragraph 4 of the OEM License:
http://www.microsoft.com/oem/sblicense/default.mspx
Jafo, if you bought your OEM XP Pro without ANY hardware, it's illegal my friend.