My computer doesn't work

Hello, I am having a problem with my computer. I was trying to install windows xp professional on my windows xp home edition. ( I borrowed my friends CD) After I brought the xp Prof. CD home, I inserted it in my cd rom drive. And then...it started to install xp prof. on my xp home. It was doing all great for about half an hour, and then all of a sudden...a blue screen came and it said " Windows is shutting down to prevent damage to your computer.....and so on..." I turned my computer off. and tried to do it again, and it came again. I turned it off, and restarted it..and then it said please insert the windows xp professional CD. When I inserted that...it did the same thing again. It's not fully installed...(xp prof.) Now whenever I start my computer, it says " setup is restarting....." and then it goes to a blank light blue screen...and then an error comes. And it restarts my computer automatically....and it KEEPS doing this again and again when I restart my computer. I cannot get to me desktop? Any help on how I can get my computer back?? to normal?? Thanks to all who help! Please do.