Well, I started messing around with it again tonight and figured it out! I did go in and check the BIOS, but my RAID was already disabled and there were no other settings that seemed applicable.
I also did move the SATA cable from the SATA2 slot to the SATA1 slot on the motherboard, but I don't think this really would have made any difference.
In the end, I think the final change that did it was this: I was in the Device Manager and selected this drive under DVD/CD-ROM drives. There was a "Region" tab and when I clicked on it, the current region was "unknown". So, I selected the 'United States', which set it to region1 and applied it. When I put in a DVD movie, it played!!
So I did make those two changes, but I think the region is what did it...
An interesting thing I noticed was on that Region tab, it mentioned that the region could only be changed 5 times, and that no matter if I moved the DVD to a different computer or reinstalled the OS, I would only get five changes in total. Is this standard? I don't even see a need to change it, but I hate being limited to something so hard and concrete....?!
Thanks for the suggestions; hope my findings can help someone else.