Hopefully the next release of the Mac OS X DeskJet driver will provide
AppleTalk support. We do not have any specific information on this nor when it will become available, but we do know that the next driver update is currently in the works. Please refer back periodically to the drivers and downloads page for your printer on our web site. You may sign up at the following web page to receive email notifications when new drivers are released.
http://subscription.support.hp.com/
You can print over AppleTalk in the Classic Environment.
Most 900 Series DeskJet can have both a USB and a parallel cable connected to the back of them at the same time, and only require a power cycle to reset the ports. Whichever port is accessed first will lock out the other port until the next power cycle. However, sometimes the printer does require that the other cable be disconnected.
The DeskJet 960, 980, and 990 have hot I/O ports which lets them automatically switch between ports when needed without a power cycle. You can call (208) 472-3494 and should be able to inquire about a possible trade-in/trade-up for the DeskJet 970, if one is available.