help old hp is givin me a headache

[bishop245]

I got my Vice presidents old hp its an athlon 3000 on an asus a7n8x-la built for hp oem installs. Now here is the problem: when I unplug the hdd I get boot disk failure even with my ubuntu disk in the drive, and a different hdd attached to the cable. The factory hdd has been makin funny noise for a few years now and I dont want it to die on me so I want to swap it out but alas when it is unplugged all I get is disk boot failure. Any clues what a stoop noob like me can do to fix this fubar hp