I burned a cd with windows xp with sp2 and it worked when I installed it on my PC. When I tried to instal it on my iMac though, I got the Error message:
CDBOOT: Couldn't find NTLDR
NTLDR is a boot support file for Windows. I've only seen that error when trying install over an old XP installation or screwing around with partitions schemes.
If the disc legit then I'd just remove the BootCamp partition and create it again. Its also possible you didn't copy all essential files when you made the disc, the NTLDR is usually a hidden file on the root (if I remember correctly).
My only suggestion for you would be to try a different Windows XP disc.. Sorry I can't be of more help, but I'm sure someone else can. Hold in there.
You might want to try making a post on the Apple support discussions.. (couldn't find the link to the BootCamp section on a quick search, but I know it's there somewhere..)