No. DVD writing isn't quite there on Linux yet, I think. Plus, the lack of a standard means I should wait. I took the DVD writer *out* of my PowerMac G4, and I'm definitely leaving it out of this box. Am considering putting in a CD-RW drive, but I'm not sure yet.
As for mixing SCSI/IDE - I don't figure it really matters as far as UNIX goes. /dev/sda3 is mounted to / and /dev/hda1 is mounted to /dave and it's all good
Some drives are faster, that's all. I'd like my main drive (operating system + programs) to be as fast as possible, but I'm willing to live with IDE for now (and maybe forever, we'll see), as explained above.