dbwillis,
Your Optiplex is substantially better than my little l550r. I believe yours has a 133MHz FSB. Mine is 100MHz. Also, the ATA speeds are a function of the North bridge. If it doesn't support ATA100, then you don't have it.
After looking up my drive's model number on Maxtor's site, I've confirmed that the drive is ATA66, so I highly doubt the mobo (810e chipset) is ATA 100.
ZABFLEX101, it looks like you are correct. 🙂 Thanks for the help, guys.