Mayo,
I use VPC 6 to operate my Garmin GPS V since Garmin refuses (and they are nasty when you ask them) to support the Mac. I run it on my dual 1GHz Mac using OS 10.2.4. I connect to the Garmin GPSV via a USB-to-Serial link (IOGear) (I can't wait until Microsoft/Intel drop the serial port sticking it to garmin). I have just downloaded LinktoGPS which is supposed to allow the GPS V to operate directly with the Mac without VPC. If that works.
Since Microsoft bought VPC frpm Connectix, there is a belief that they will drop VPC. Also, I understand VPC will not run on the G% and/or Panther. I will be checking that out when I get my G5 up and running.
MamaMoose