What's happening within Wndows itself Akira-is the drive still showing?
Also,check your BIOS & see if you have a setting to enable SMART monitoring-When my old 2.1Gb drive was dying on my old Compaq crapbox,I got warning messages before it died.
And as Shadowfire said,you should have at least UDMA 33 too-whether the DMA is enabled or not is another matter.
Silly question,but have you double checked all your connection's? Unplugging & replugging can be a hassle to refit things again sometimes.