its true! - you can't successfully install WinXP with an SP1 disk on a MacBookPro and BootCamp :-(
However - I've managed to get WinXP booting, manually installed the ATI video drivers, ethernet and wireless networking drivers! So now I'm attempting to upgrade via the Net to SP2 and reinstall the Mac hardware drivers from the Boot Camp drivers CD - here's hoping! A full WinXPSP2 install disk retails for $645, so I'd rather not blow that much out of the budget without exhausting other possibilities first!