I had a problem with my first install as well. To get back to XP I used fdisk to restore the mbr (can't remember the exact command, but you should be able to find that on the net) and then I did a fresh install of Linux
I have to warn you though, with me grub works perfectly now, but only after I had completely reinstalled XP. Couldn't tell you why, but apparently xp had done something weird to the mbr so grub didn't work, which wasn't so on the second install.
The grub config seems ol though, wouldn't change that.
Some will say to use the xp bootloader but that seems to me like a lot of innecesary work.