Go for the IBM DeskStar 48H, it’s the fastest (5400rpm) 2.5 drive on the market, plus has the most storage space (for it’s size). As for the FireWire enclosure get one that has the Oxford 911 chip; this chip speeds up the transfer rates. Both items can be bought from Transintl.com (and others) the drive is about $440 and the enclosure is $125. Plus with the enclosure you won’t need an external power source, it’ll draw its power from the FireWire port, but it also includes an AC adapter in case you need it.
But since the PB G4 has only one FireWire port, I’m not sure if you’ll need an external power source, since you’ll need to connect the DV camera to the other FireWire port provided on the drive enclosure.
Go to
www.xlr8yourmac.com and look up some of the past articles dealing with the PB G4s FireWire ports, there’s a ton of information on that website.