If you have another working PC with a CD burner, download the live version of ubuntu linux and burn it to CD. Then start the PC with the CD in the drive and once you have the live screen, bring up a terminal window. This assumes that the first drive on your system is /dev/sda (most likely). Run "fdisk /dev/sda" and create a new partition table, then write it to disk. Shut down Ubuntu and you should now be able to install Windows after rebooting with the Windows install CD inserted in the drive.