Yes, you will need to edit the boot.ini to add another line under the [Operating systems] section so you can boot to Vista and no, it doesn't matter that they are different drive types but you can always check your BIOS and choose which drive the system looks first (SATA or IDE) then edit the boot.ini for that OS.
This KB article from Microsoft will assist in walking through the process. You'll just need to make the necessary adjustments for your specific system.
Second, Have you even tried booting from the Vista drive since you cleaned the virus to see if Vista still works? If it does and you don't need the XP drive anymore you can always remove it from the PC and just leave the Vista drive to boot from.
Hello, im a bit of a noob,
i installed vista then i got viruses and it wood not boot.
so i installed xp on 2nd hdd and removed the viruses from the 1st hdd.
i thought there would be a menu to pick which OS to use but i cannot see one.
now i cannot get back into vista on my first hdd
do i have to edit boot.ini or edit something else.
also one of the hdds is sata 1 and other is ide 1