Maybe you should install Linux on the master drive and Vista on the slave drive,but install Vista first.Also,you can create three partitions on the master drive after you have installed Vista on the slave drive,one for /root,one for /home and one for swap space(2xRAM).You can do this from Windows(I think some Norton partition manager can make Linux partitions-meaning it can create ext3 file systems on those partitions) but you can use other partition managers and create three partitions on the slave drive without the file system on them.So when you're installing for example Ubuntu you'll need to choose manual partitioning and then select partitions that you've created earlier for Ubuntu to be installed on.Install Grub on the MBR.If all goes well and you're in Ubuntu desktop edit Grub's menu.lst file with command;
sudo gedit /boot/grub/menu.lst
and you will do this by opening the terminal,entering command,then your password and hiting <enter>.Then add this to the file;
title Windows Vista (loader)
map (hd0,0) (hd1,0)
map (hd1,0) (hd0,0)
save the file and reboot.Now when computer starts you should have the option to start Vista or Ubuntu.
You can try all of this without reinstalling Vista,just create partitions as I've said and do what I've said afterwards,but without entering the second code in menu.lst file,but if ain't workin' try to enter it there.
Maybe you'll need to change letter h in the second code posted here to s in maps lines,it depends on your hard drive.
If all of this looks to you like a atom physic,just give your best,you can do it.