Thanks for the help.
It got my DVD drives working again. However, when I started up iTunes (v10) it gave me an error message saying:
"Warning! The registry settings used by the iTunes drivers for importing and burning CDs and DVDs are missing. This can happen as a result of installing other CD burning software. Please reinstall iTunes."
I tried importing a music CD into iTunes, and the internal DVD drive crapped out after successfully recording the first song and getting halfway through the second (and taking far longer than normal). The new external DVD drive I purchased was able (slowly) to import the entire CD.
So I checked Apple's troubleshooting and found the following article that recommended leaving in the UpperFilter but modifying it to support iTunes.
http://support.apple.com/kb/TS3299
After adding UpperFilter back to the registry, and modifying it per Apple's instructions, everything worked normally.
Thanks for your help, I definitely would not have gotten anywhere without that start (modifying the registry).
Jason.