Additionally to what Allan stated, if he doesn't need 1TB storage, another option is to purchase and install a SSD drive and install clean to that using the factory system recovery software that you might have or may still be able to burn to a set of DVD-R's or make a bootable usb stick.
There is a drastic performance increase between a HDD and a SSD. I have had Windows 7 to desktop ready to roll on a Dual-core 6 year old 2.3Ghz system 13.5 seconds with a 90GB SSD, and with 500GB HDD it took 52 seconds prior.