Thanks for everyone for responding. Here are the steps I took to get it done.
1. Boot from my Ubuntu 10.10 Live CD
2. Mount my 2 partitions
2. Create a 10GB partition on my external hd to copy my /home folder to.
to copy the /home folder. (I actually forgot to do this step, I realized that I had forgotten too late, during step 5.)
sudo cp -a /media/Ubuntu/home/* /media/Backup
4. Use GParted to clone my Windows XP partition to my external hd.
5. Use GParted to move and shrink my WinXP partition and move and grow my Ubuntu one.
6. Ran the code to reinstall Grub2 on my hd:
sudo mount /dev/sda1 /mnt
sudo grub-install --root-directory=/mnt /dev/sda
It rebooted fine, and I'm back to normal with much more space to run with. I did the sizes at about 50/50, so its fair now. I haven't booted WinXP yet, but I don't expect any problems; I can open the partition in nautilus fine. Thanks for helping me out!