I need to reinstall windows on my machine to fix a few things, but whenever try to, the installation program says (after booting from the cd and all) that a hard drive could not be detected on my machine and that the installation was aborted because of that, which is weird because I just remove the windows cd and boot to the hard drive just fine, what should I do?

it is a dimension 8400, 3.2 ghz, 1 gig of ram, X800 SE, 160GB SATA HD