"You always recommend recording on a separate drive than the one used by the system. Since it is impossible to put an Ultra Wide SCSI on a Powerbook, is FireWire a possible alternative?"
Like we said yesterday, technology, and information relating to it, is a moving target. Early testing we did with FireWire drives did not yield good results. However recent tests have showed much more promise, and in many cases we are finding they work fine. As you may know, we won't carry products that don't get our fully-tested seal of approval; as a result of our testing we will now carry the FireWire drives that meet our standards. Based on these tests the X-Project FireWire drive from Glyph is proving to be excellent on G4 machines with systems like Digi001 and MOTU 2408, but on some G3's (many of which have slower Firewire ports) it's not as reliable. So, will one work with your Powerbook? I would try it. Depending upon how hard you use your system it will probably be okay.
The inevitable next question is, how do they work on TDM Pro Tools? Well, Digi is not even close to approving them, but we've actually seen some work. However, even though we are all always looking to save as much money as we can, if you're getting into a TDM Pro Tools system we recommend you stick with what we KNOW works and what they have approved. You're spending too much money to try to cut corners on hard drives.