Slow hard drive

I just wanted to post a solution to a problem I had with a slow slave hard drive.  It worked fine as far as reading and writing data, but it was too slow to use for video editing.  I had gone through the normal drive installation instructions when I added the drive (Western Digital).  I recently found that the Dell BIOS (accessed with F2 during boot) was set (under Drive Configuration) Primary Slave Drive OFF.  I turned it on by scrolling to it and toggling it to Auto with the right arrow key.  I used the freeware "Roadkill's Disk Speed" utility to see the difference.  I had two surprises.  One was that the slave drive worked in the first place with the BIOS turned off.  The second was that the change significantly increased the speed of the Master drive too.  The Master drive linear read speed went from 24 MB/sec to 48 MB/sec and the slave from 2 MB/sec to 41 MB/sec.  The random read speed only went up slightly on the Master (2.7 to 3.0 MB/sec), but the Slave random read increased from 0.9 to 3.2 MB/sec.  Access time for both the Master and Slave did not change (about 9 ms).  For the record, the Master disk drive spec is 100 MB/sec maximum buffer to host transfer rate with Ultra DMA Mode 5, which my Device Manager indicates is used for the Primary IDE channel (the Secondary IDE channel is DMA Mode 2 and 4 for Devices 0 and 1).  I hope this helps somebody with a similar problem.