Hi there... just wanted to share the transferring of my original hard drive to another computer, as the original computer popped it's cork. After installing the original drive in the new computer and booting, I couldn't see grub, XP, or the PcLOS that I have been using for a few months. Everything originally was working great, the computer blew up (old one anyway), just transferred the drive over, and now no booting of any grub.OK.... here's how the problem was solved:
1. Booted from the original XP CD and chose the 'Second' repair provision which fixed the XP boot.(left my files intact)
2. Booted then from the PCLinuxOS 2010 live CD, did a fresh desktop install of PcLOS
'without formatting anything' which also reinstalled grub, rebooted and grub came up with my XP and PcLinux choices again.... everything seems OK so far...

Basically didn't have to do any re-selecting partitions, settings etc. It worked for me, I hope it works for you!!