I Need Help !

I think I screwed up big time. Heres my situation. On step four, I typed in the four commands but in the first command I typed in E since I thought I had to put in the disk drive in which XP was installed. (PLEASE DONT SAY MY COMPUTER IS DONE). So when I rebooted it, it went to an blue error screen. So Vista doesn't boot anymore, not even with the installation disc. AT ALL. So I was able to boot the computer with the xp installation cd. I deleted the disk drive and reinstalled xp only. But it still doesnt start up the way it should and I cant install vista no more.
I hope you can help. Thanks in advance.