Is your Vista currently using a RAID configuration? In order to get a clearer picture of your setup, how about booting your Live CD (the Ubuntu install CD), open a terminal (Applications > Accessories > Terminal) and do:
That will create a "RESULTS.txt" file in the same directory from where the script is run, namely your desktop; please copy/paste the contents of that file to your next post. That will help clarify your setup and hopefully what your problem might be.
cd ~/Desktop && wget 'http://home.comcast.net/~ubuntu_grub/boot_info_script.txt' && sudo bash boot_info_script.txt