Computer help: How do you install WinXP on a new system with Vista pre load

Booting with Vista.

The easiest way to do it without having confusion while using the machine would be to have a second hard drive with the same specs as the original, same brand, size, speed everything. That way the computer doesnt have to reconfigure for the new drive type every time you swap the drive. It would work even with a different drive but we are looking for simplicity here. Then install a removable caddy that supports the drive type you have allready and thus the new drive, makes sure to plug the caddy drive cable into the same port the original hard disk was connected to. Now just put in the new drive in the caddy that is turn on the machine with a copy of win XP in the CD rom or dvd rom with the bios set to boot from it. Load xp and set it up as you would normally. If you want to use Vista, which I for sure wouldnt understand as I have it and brother,,well I'll skip that,,anyway whatever system you want to use just put that drive in before you turn on the machine. I use EZ Swap2 Caddys. They are fast reliable, hot swappable if your motherboard supports it and best of all they use Direct Connect inside so you never have to mess with plugging anything in. Just slip in the drive and turn on the machine. I have been doing this since the first betas of Vista came out and have had no problems at all. None ,,, nota,,,,zilch and thats good. I even have a raid0 stripe drive that has all my music and photos and data files that I use and it works (all the data) equally well with either OS. So I dont have to have dupes of 125 gigs of tunes, vids and photos. Good luck. There are for sure other ways but none as simple if you can afford the caddy and another drive.