personally i use my gps (garmin eTrex Legend) with my laptops, and pda (depending on what I feel like)... also on a few different operating systems (you know, windows, linux, pc2002...), at the time I got my gps I thought about all of this, and figured I had chosen correctly since I haven't had any problems with the gps because of the serial interface that works with everyone of my configurations... and that is just damned skippy.
(the only issues I have had relating to the gps connection has of course been the usbserial things that were jacking with me on xp and linux at different points in time... )... alas.