You say you downloaded Boot Camp, but Boot Camp hasn't been available as a download since it was in beta in 10.4 Tiger. If you're using the beta with Tiger, now is a good time to move on.
I have a feeling that you've inadvertently erased your HFS volume with OS X on it, recovering it won't be an easy task. If you boot up off the Mac OS X Install DVD, and run Disk Utility, what partitions does it list there? Hopefully you made a Time Machine backup!