Go to device manager and click on the IDE ATA/ATAPI Controller. Then select properties for the primary IDE Channel and under the "Advanced Settings" tab, select "DMA if available". Do this for both channels. Reboot and check in the same "Advanced Settings" field for the "Current Transfer Mode". Should be changed to DMA or ultra DMA.
Also make sure, that you're using the right ATA 66/ATA 100 cables.