Hya Roper.
What O.S. do you use? And can you boot of youre windows disc?
I think the best thing to do is boot from the windows cd or a bootdisk and then delete the existing partition(s) , recreate them and then format and install windows.
If that doesn't work the you can try to formatt the HD with this app from floppie:
http://www.killdisk.com/downloadfree.htm
And then try to install windows.
Also maybe the cmos has to be reset , you can do that by removing the pc's powercord and then the motherboards battery for a minute , then replace them and start the pc again.