GRUB Loading stage1.5.My first attempt was to boot up an XP install CD and try to run FIXMBR. But since it's my company's work laptop, I don't know the local Administrator account's password so I can't even get into the recovery console at all. I was thinking of pulling together all the pieces to download a DOS or Windows 98 floppy image and boot from that to run FDISK /MBR, which supposedly will still work to boot Windows XP.
GRUB loading, please wait...
Then I had my first useful idea in all of this. Knoppix. I popped in an old Knoppix DVD and booted it up. I struggled for a bit with trying to find an XP MBR to dd onto my laptop hard drive, thinking "surely there's an archive of MBRs out there on the net". Then I stumbled across my final answer, ms-sys. Ms-sys can write any of the Microsoft MBR's to a hard drive. I ran "ms-sys -m /dev/sda" and rebooted. Windows XP came up fine.
I've since gone back and tried to make Ubuntu boot from that portable USB drive, but I can't get a machine to even get to the boot loader no matter how I fiddle with the partition table. Maybe I need to try a different drive. I'd love to have a full-blown Ubuntu install on a bootable USB drive, especially since Wifi support finally works so well.