A thing I would check first:
- BIOS is using the right drive to boot from?
(My Asus motherboards (with VIA chipset) respond better to swapping SATA cable positions then adjusted setting in BIOS.)
The IDE drive has at least one (primary) partition that is "active". This means that the Windows bootloader will turn to that partition to boot from. However, it gets really confused when you have two drives that have both an "active" partition. Don't know if XP allows you to deactivate it's boot partition, else you could do that, trun XP off, move the drive to the Vista machine and see if the Vista boot loader will use the correct drive to start from. A good
partition manager would be able to deactivate the partition as well as restoring the activation if this doesn't work.
By putting the IDE drive into çable select' mode (normally there are instructions on the drive on how to do this, but it is more than likely that removing the jumper next to IDE cable will do the trick) the BIOS will figure out where the drive should be. It's an option to try.
What you should have done is the following:
- Build the two harddisks into the Vista machine.
- Make sure both drives are visible in the BIOS
- Install XP on the old drive
- Install Vista on the new drive
In my experience (with Win98-Win2000 dual boot systems) it is the oldest Windows edition that has to be installed first and let the bootloader from the newer Windows edition sort it out.
Having said all this I must mention that I don't like the concept of dual-booting Windows at all. The novelty wears off quickly and I assure you that your friend will be working in the latest and "greatest" product from the Redmond stables sooner than you and he/she thinks.