Ubuntu Installation :: Neither BIOS Nor WinXP Recognize 10.10 Partition

I'm trying to install Ubuntu 10.10 on my WinXP desktop computer. I used the LiveCD and manually configured the partitions. I resized my XP partition (the entire SATA HDD) and created a 37GB partition for Ubuntu, as well as a 3GB swap file. I installed the boot loader on the Ubuntu partition. But BIOS doesn't recognize that the drive has separate partitions, and I can't boot into it from Windows either. I know I didn't modify WinXP's MBR, but should I have? I didn't know where it was.

I booted into the LiveCD again, and went into the disk manager. I Edited the Ubuntu partition and saw a checkbox that said "Bootable". I checked it and hit apply, hoping that might do it. I waited twenty minutes and the little circle was still spinning with no indication that it was actually doing anything or any warning of how long it would take, so I rebooted. Still no luck.

Someone told me that Ubuntu sometimes won't be bootable if you have both SATA and PATA drives in the system, which I do (although both XP and Ubuntu are on the same, SATA drive) and gave me a page that told me to use Grub4Dos. I fiddled around with that, only to come onto the Ubuntu website and find out that the page they gave me was outdated, before Ubuntu used GRUB2.