Unfortunately that may be why you are not seeing a distro load since it was configured into the mbr of the drive other then the one currently set as the default. With the Windows installer if an ide drive is present the boot files are automatically placed there even while seeing the Windows files and directories created on a separate sata drive.
The ide drive is seen as the first drive on the system for Windows while the boot loader for Linux depends on a few other things. When installing a distro on the default sata(one of two seeing Vista) it added XP in(second sata). The live cd install saw Vista knocked out while finishing the stage 2 like Windows sees on the first boot up once all setup files are copied to the main drive.
When going to install all over again seeing the distro installed on the XP drive it added the Vista loader(Grub4Dos used for the dual boot) in as a boot option. That failed to see stage 2 however with repeated attempts with the live for cd version of ubuntu Gutsy 7.10.
The root partition if you are using the install option on the live cd has to be defined as the mounting point by highlighting the root itself being an ext3 type partition(both primary and extended tried here) with the "/" item selected when choosing the edit button. With Grub seeing a good install into the mbr you should see something like this when first booting.
ubuntu 7.10
ubuntu 7.10 (recovery mode)
ubuntu 7.10 memtest
Windows XP or Vista(depending on version)
Windows XP or Vista(second identical listing)