playing with vista in a dual boot scenario

I'm a bit of computer-aholic, at least when it comes to trying new things or building a new machine. I just enjoy it. My lastest endeavor is taking two Pentium 4 computersand migrating components into one case utilizing the best processor, video card, etc. The difficult part is to preserve the Operating systems with these hardware changes. luckily the motherboard which is connected to the hard drives housing the operating systems is the one I'll use, but I'll take the faster processor out of the other. Anyway, I've yet to migrate components, but I do have a dual boot scenario. I started with a single 80GB hard drive with Windows XP home edition. I then added a 120gb and a 200gb hard drive. The windows home edition had a script error causing problems and I forgot about it when I install Vista Home Premium on the 120gb hard drive allowing me to dual boot either XP or Vista. But its an experimental setup anyway, so I wasn't worried. I then working around the script error setup both operating systems to use the 200gb hard disk to house files, ie my documents, my pictures, etc. This worked quite well, but the script error kept bugging me. So I had a bright idea, lets load XP home edition and the upgrade to windows XP professional. The upgrade went through quickly and almost without a hitch. The problem I had after the install was that my dual boot menu was gone and the computer loaded directly into Windows XP. But I found a solution and it is so easy, I have to give credit to microsoft. This what I did, I booted with my Vista disc, and instead of clicking install I selected repair my computer. It then gave me a list of operating systems, note this tool will not detect any version but Vista, I selected Vista hit next and then it gives me options on what to repair. The first option is to repair start up options and that was the issue so I ran the tool and bingo. The system now runs win xp pro and vista home premium. I will post later on, when I finally get the chance to migrate my systems.