wErd I had the same error. I just replaced the cable from the mobo to the hard disk and it worked.
I had my computer just sitting in my bedroom and I'd just glance at it daily, and I was too lazy to fix it. So about a week ago I decided i'll fire it up, and I got windows installaled yay.
My computer was not nearly as cool as yours, mine started out as a 800 mhz 64 mb 10 gigs of space computer. Its now 250 gigs, 512 ram, and still 800 mhz. But this computer will run any program out there (photoshop, grand theft auto, halo) I just use this computer whenever I just wanna chill in my bedroom and listen to music, or my dads on the good computer.