Aloha firefly2002,
I have a PowerMac G4 Gigabit Ethernet, but I only have one DVD slot - the other one was made for a Zip drive (which I have yet to uninstall) - the metal carrier, which fits inside the computer itself, is shaped to only accept a full-size 3.5" optical drive and a Zip drive underneath (see the attachment). I think the Quicksilver and later models actually let the owner install two optical drives, but not in the Gigabit Ethernet model, and probably the Sawtooth model as well. I don't know about the Digital Audio model - it really depends on the model of PowerMac G4.
That being said, I can only run up to Tiger on my PMG4, so I'm OK with only one optical drive. I'm still not sure how I want to use it - some people use theirs as a file server, others as a network server (using Mac OS X Server). I let my nieces and nephew play online games (disney.com, nick.com, barbie.com, etc...) on it, as I don't have to worry about viruses, spyware, or other malicious Windows malware. Also, I just like the idea of replacing yet another Windows PC with a Mac!
HawaiiMacAddict