as I'm may not be picturing this correctly. It sounds as if Vista isn't even on either drive now. If so you may just have a problem with the boot.ini file on the XP drive. See if it has a line still referencing Vista. If so, remove that line.
I have an HP Pavilion a1210n running XP. A while back I added a second hard drive so I could put different OS's on it to study for college. I was hoping to dual boot. The first OS that I put on the second drive was Vista and everything was fine for a while until it came time to put something else on my second drive. I figured to put a new OS on the drive I needed to delete the partitions on the second drive, repartition it, and install the new OS. I had Ubuntu (not sure which version) on there and the second drive currently has Windows Server 2000 installed.
The problem I'm having is that whenever I boot I get a screen that allows me to either boot into Vista or an earlier version of Windows. I always have to select the earlier version of Windows option otherwise it tries to boot into Vista after about 10 seconds. When it boot into Vista it says "Windows failed to start. Recent hardware or software changes may be the cause." It then instructs me to use the recovery disk to repair it and gives me this info:
Info: The selected entry could not be loaded because the application is missing or corrupt.
I would like to be able to dual boot without all this Vista nonsense. Server 2000 is on my second drive now and I believe I will be putting a version on Linux on there again soon.
Also of note, ever since I deleted Vista on the second drive I now have to open my computer and disconnect the hard drive that came with the computer (leaving the second drive plugged in) to boot into my second OS. It's a pain.
Any advice would be great. Thank you.