3 different versions of windows xp

Which one is best? I don't get it...

Windows XP Home OEM with Service Pack 2
Windows XP Home Retail with Service Pack 2
Windows XP Home Upgrade with Service Pack 2

The OEM version is what usually comes with premade computers.
Retail is the full version you can buy.
The Upgrade version requires an old, full/retail version of windows (98, me, 95, 2000, etc.) when you install to make sure that you really own a windows OS. This version is cheaper than the retail version.

BTW thanks for starting the thread in the right section this time... :)

So my computer had come with windows xp when I got it so that would make it oem? And would that come with a bunch of crap if I were to install that? If I were to use the Full Retail would that be better then the OEM? Last question.. If my computer is OEM would would my working cd key work with a retail?

Not sure about XP, but in 98 my oem key wouldn't work with retail versions..

If I were to use a nonlegit cd key are there ways to get updates and everything normally?

Yes, you can disable the Windows genuine authentication in the ActiveX options before you update your windows.. Microsoft is so good to us sometimes.