Thanks for the replies. Investigating now...
I'm using an nForce2 motherboard, and here are the hdparm -Tt /dev/hda results:
(Disk is IBM 75GXP...reads should max out at somewhere close to 30MB/sec sustained...)
Oh, yeah, the hdparm -d1 /dev/hda definitely worked.
I went ahead and inserted the commands (for HD and DVD/CD-RW drives into the rc.local file, and now it all works great. Thanks again