Now it boots straight into Vista's bootloader, right? Perhaps it's messing up with placing the bootloader in the MBR. Grub works by placing a small record of itself in the MRB then keeping the vast majority of its data, including the boot image list, in /boot on your Linux partition.
Try this:
Boot up the Live CD. Does it mount your Linux partition automatically? If not mount it like so:
mkdir ~/Desktop/root
sudo mount -t ext3 /dev/hda1 /home/kubuntu/Desktop/root
What that does in the first line is make a directory on your desktop in which you can mount the partition. In the second line you mount the ext3 formatted partition. If your filesystem or partition location is different change this to match.
Once you've got it mounted and ready for your perusal, navigate to /home/kubuntu/Desktop/root/boot/grub and open up your menu.lst. This file is the file that contains the list used to define the bootable devices. Is it there? What does it say?