well i installed windows server 2003 standard edition with service pack 1 and 2, works like a dream. this is on my 150gb sata drive.
then installed xp pro on my 80gb ide drive, so now at login i get the MS duel o/s screen but when i select server it shows the progress bar then freezes at the end and wont load.
That sounds like the whole install has issues.
Normally people have problems with the MBR when dual booting but seeing as you get your o/s selection and it crashes when booting kinda points the finger somewhere else.
i think you need to decide which OS has control of the bootloader, clean install each OS to separate HDD then connect both HDD’s, get the OS to recognise the other HDD and edit boot.ini in the root directory of your chosen OS tto add the other OS to the bootloader