Ubuntu LiveCD install stuck on "creating user" step

I've been STRUGGLING to install Ubuntu (as dual-boot with an existing Windows XP installation, on a different drive and partition) for a couple of days now. I've already checked the md5 hash for the downloaded iso and DVD files after burning.

I have several problems that recur with my installation:

1. At first, my install would go slow as molasses, with only theoccasional sluggish sign of activity (DVD/HD lights, etc.) beforegetting stuck at various points early in the process. I researchedand found that often NVidia cards are the culprit (which I have). So I tried the nomodeset option, and that finally seemed to getthings going (DVD/HD lights flashing regularly, progress indicatorprogressing, etc.) But then the install always froze at the"Creating User" step. Per another forum post, I've been trying toredo the process doing a "noquiet" so I can find out exactly whichstep is causing the issue, but I haven't been able to because...

2. Now when I try to either boot from the DVD or run the installprogram, I get the error messages:

   buffer I/O error on device sr1, sector nnnn.

   ata_id[257]: HDIO_GET_IDENTITY failed for '/dev/sr1/': No message of desired type.

   (initramfs) Unable to find live file system.

   At first I thought it was due to the earlier faulty installs: Iwent back in Windows to clear out the intended Ubuntu partitions (regular and swap). But now Iam wondering if this is due to the DVD drive: it appears to freezeduring the boot process and not respond in time. A "noquiet"boot-run reveals error messages like "soft resetting link...ata slowto respond...forcing hard reset...etc." As a test, one time I triedto eject the DVD during the process when things got stuck: it wouldnot respond until the boot process finished failing and I was forcedto reboot. This is all odd because this DVD drive worked finepreviously in attempted installs, and still works fine in WindowsXP! And 'nomodeset' does not work for me this time.

Note that my BIOS must be one of the older ones: it has options for enabling "legacy support" for USB, but there are absolutely no menus/options for enabling boot from a USB device, so that workaround is out.

Now my friends and relatives are looking at me cross-eyed for the idea of trying Linux at all (especially since they've had easier times with their MS installs).