I messed up...

So I'm pretty sure I know exactly the mistake I made, I'm just having difficulty solving the problem.

So I read a guide somewhere on how to setup dual-booting into Windows 7 and Vista, followed it exactly and I did manage to get Windows 7 to boot fine. Unfortunately, when I tried to boot into Vista, I got a black screen and then a very brief BSOD before it would return to the bootloader.

What I've realized is, this guide didn't tell me to give my created Windows 7 partition a drive letter; when I boot into 7, it calls itself C:, and that's what my Vista partition was. Complicating things further, I assigned my Vista partition to G: after the successful Windows 7 install in order to get access to it within 7.

What can I do about this? If it means uninstalling and re-installing Windows 7 that's completely fine, I just need to be able to boot into Vista again.

And if it means anything, I've downloaded a Vista recovery disc and I can boot that, I just don't know what I would do within it.

Okay. This is starting to get weird.

I let the repair disc do its thing, it said it found something, repaired it, and if I reboot my computer and select Vista, it'll load, go to a screen where it says "Installing update 3 of 3: 0%" and it will restart right back to the bootloader. If I pick Windows 7, I get a black screen, and it again goes right back to the bootloader. I can still use my repair disc, but it doesn't detect a problem.

I'm stumped at this point.

I should add that I am able to run a command prompt through the recovery disc as well..

Yeah, it's a brand new HP laptop and they insist on not shipping the Vista discs with the computers, damn them.

But in the command prompt in BCDEDIT, I noticed something kind of strange. Under both the Windows 7 and Windows Vista entries, "device partition=C:", and "osdevice" has Windows 7 as C, and Vista as D.

Could this be what's going on?

I'll do anything to be able to boot into either 7 or Vista at this point.

Okay, I might have gotten somewhere. I was mucking around in the command prompt I could run after clicking System Restore and having nothing happen, and 15 minutes later, I'm apparently initiating a system restore to a few days ago before I got myself into this mess. I might be good, I'll keep you posted, but thanks so far.

Alright, booting into Vista now with no problems whatsoever. It just took an ungodly amount of time for the System Recovery on the recovery disc to show up and give me some options.

Thanks so much for the help! I'll be sure to not make this mistake again..