At the suggestion of a friend, I recently installed a *copy* of Vista Ultimate on my second hard drive.. When booting up my system, I go through the steps in which I can select which hard drive I want to boot from.. when I select the one with vista on is it gives me a load OS error of the sort.
Does anyone know how to over come this, am I forgetting to do something?

Reload XP and wait for Windows 7 to be released.

What do you mean by copy?

Maybe your boot sector got messed up. Dual booting with other versions of Windows can be a tricky process, and the installations usually have to be done in a certain order. The master boot record can be repaired with a Vista disc (dunno about copied discs, though), but it might wipe out access to the other installation(s) on your other drive(s).

On second thought, also make sure the Vista drive is your first drive in the hard drive boot order. Some mobos have two menus, one to tell it to read the optical drive and maybe floppy drive before the hard drive, and another menu which specifies the actual boot order or all hard drives in the system. As far as I know, Vista likes to be the first drive to be booted from, because that is where its MBR is stored.

I saw this once and searched all over the net only to find it had something to do with boot order of my devices and my CD-ROM drive having a CD in it. I know that sounds stupid but seriously make sure everything is in the right order and that you don't have non-bootable media in CD-ROM if it's in the boot order.