My 867MHz PowerBook G4 still works reasonably well, especially after I upgraded the hard drive. The worst thing with it, is that it only has USB 1.1-ports. For external hard drives, iPod syncronization and digital cameras, USB 1.1 is really too slow. Miserable as I am, I ordered a very cheap USB 2.0 PCMCIA card, rumored to work well in Mac OS X. The card model reads: “AKE USB2.0 Cardbus BC168“.
Does it work with Mac OS X (10.5.8)? YES!
I inserted it into my G4. After a few seconds I got a little icon in the menu bar, next to the bluetooth menu. The first menu item says “Unknown Vendor USB Controller”. The card works perfectly, immediately, without any need to install any drivers! PCMCIA cannot provide very much electrical current, so if you need extra power there is a little cable that you connect from one of your USB 1.1 ports to your PCMCIA card (USB memory, digital camera, iPod nano is fine without; 2.5inch external hard drive needs extra power).
How about performance? Well, copying files to and from an external hard drive gives me transfer rates of about 15Mb/s, with no significant CPU load. I like it!