Need help fixing vista


Hey i got a new laptop it is a HP Pavilion dv6000. I installed Backtrack and fedora core 9. Backtrack and Fedora worked fine and vista would do the load screen and then go black and not move. So i tried to zap the MBR with something i found in another post. It was

sudo dd if=/dev/zero of=/dev/sda bs=446 count=1
now i start the pc and it just goes to a black screen and stops, how do i reverse what i did so i can get back to grub and how to i get vista to work. I already tried the recovery disk all it does is go to a black screen and says Windows is loading files then it boots vista's loading screen and then goes black. Any suggestions?
Hey thanks for the help, i acually just wound up downgrading to XP and getting drivers. From there i installed backtrack and fedora core.

Thanks for the help though