Uninstalling vista (unable to locate drive)

I installed Vista roughly 3 weeks ago and all I have been having is problems,
so, I decided to go back to XP. The switch back gets interupted after I boot
with the CD and begin installation, it get's as far as starting windows then
it tells me that it doesn't recognize any of my hard drives (I have 2). after
this I tried switching all of the files i wanted to keep to my secondary try
and boot with a dos startup disk and format that way. Again it cannot find
any of my hard drives, partitioning doesn't work. I tried installing Linux
Ubuntu same problem... Can someone please help me I'm getting really
frustrated. I'm moving to a new city in 6 weeks and am counting on being
able to apply online. however the attach files button or any browse for that
matter doesn't work for me.