Yes. What you said seemed to be true. Strangely, it detected my second 640G as /dev/sdb & it allows install into that but grey out the first /dev/sda.
After installing 9.10 & found couple of unresolved bugs, I pop in the old 8.10 cd & install it on /dev/sda & it goes without problem.
It seemed ubuntu 9.10 is relatively unpolished compared to previous releases.
Bugs encountered so far are:
1. No sound upon reboot. Reason, grub did not activate the latest kernel in grub.conf. Doing sudo apt-get install grub2 resolve that.
2. Webcam works well in cheese but not in skype. Tried couple options, futile.
3. tvtime, failed to work, may be related to 2.
Upgraded 8.10 & use back 9.04 for the time being.
Try using the Alternate install disk (if you aren't already), there appears to be a problem with some nVidia chip sets and the live/install disk.