Progress towards installing Ubuntu on Windows comp

This machine (home-made, AMD, Pentium IV, 512 MB RAM, SiS190 Ethernet card, 20 GB HDD) has Windows XP installed. However as only about half of the HDD space is taken up by Windows, there's an opportunity to install Linux.
An earlier attempt at this failed due, apparently, to the non-bootability of the DVD drive (two optical drives, one for DVD other for CD).
However, the puzzling thing was that both optical drives show up in the BIOS boot order so it's strange they don't boot.
I had posted to a Windows XP forum on this and the idea that I have a non-bootable optical drive didn't seem to be taken to seriously. However, some suggestions were made.
In all, I considered various routes to getting GParted to partition the HD in order to accommodate Ubuntu including:
1. Use Netboot.me booted from floppy to run GParted (progress is being made here and I'm expecting a new version of netbootme.dsk that will work with the SiS190 ethernet card on this computer. The ones I've received so far have "almost" worked.)
2. Include CD-ROM drivers on floppy boot disk which should allow the floppy to boot the CD with the GParted ISO. Haven't quite found how to do this yet.
3. Upgrade BIOS which may make CD-ROM bootable. To do this, I was using this very detailed tutorial. To get the motherboard manufacturer and Model number I downloaded and installed Sandra.

However, largely due to the doubts expressed in the replies to my forum post regarding the non-bootability of my CD-ROMs, I decided to try again.
So, I downloaded Partition Magic, burnt it to a CD-RW and this time I used the CD, rather than the DVD drive. I set the boot oredr to be CR-ROM >> DVD-ROM >> HDD
and whatdoyaknow, this time it booted and I was able to play with Parted Magic on this Windows machine. So, that's a huge breakthrough.
My intention is to install a Windows XP/Ubuntu Jaunty dual boot system on this computer tomorrow.