XP was not even a gleam in the eye of Microsoft when the TP600 was announced which is why I suspect that the IBM (Lenovo) site does not have much to say on the matter. (It is a very old box nowadays.) You need to get it back to an OS that the BIOS does support e.g. W98 and then update the BIOS to support WinXP. (The moral of this is RTFM BEFORE you dive in.)
BTW. I sold hundreds of TP600s and a very good box it was - but that was a VERY long time ago.
t
November 2007