I was reading the shoutbox regarding your recent drive troubles, it's never good when that happens. Whatever is really happening there, it's definitely quite odd. XP should be able to recognise any partitioned amount out of the box, service pack or not. I use an original XP disc and it's recognised 200gb partitions without a problem. It is, of course, subject to any BIOS limitations, but since I think you're using something made after 1998 you really shouldn't have a problem.
Maybe it's the hard drive controller if both drives seem to have gone... is there another drive you can test it with at all??