to enable dma mode go to>
1.start menu
2.control panel.(classic view here)
3.administrative tools
4.computer management
5.In the left pane select device manager.Then in the right pane
double-click IDE ATA/ATAPI Controllers to display the list of controllers and channels.
6.Right-click the icon for the channel to which the device is connected, select Properties, and then click the Advanced Settings tab.
7.In the Current Transfer Mode drop-down box, select DMA if Available if the current setting is "PIO Only."
8.If the drop-down box already shows "DMA if Available" but the current transfer mode is PIO, then the user must toggle the settings. That is:
Change the selection from "DMA if available" to PIO only, and click OK.
Then repeat the steps above to change the selection to DMA if Available.
For information on these modes go here-
pio
http://en.wikipedia.org/wiki/Programmed_input/output
dma
http://en.wikipedia.org/wiki/Direct_memory_access
please rep me if this helps