NTLDR is missing; Please restart (Win XP)

HI. I have obtained an old PC (HP Brio 8 series machine) which is originally pre-nstalled with red hat Linux from a friend. I formatted the HD and hooked up the HD to a PC then installed Win XP SP2 on it. When hooked the HD back to the machine and start it up, the message “ntldr is missing, please restart came up”. I have googled and found alot advices on this including the fixntldr program from tinyempire.com/notes/ntldrismissing.htm but the problem still persist (edit boot.ini, copy ntldr and ntdetect.com, etc.). I would appreciate very much if anyone has any other ideas.