Schopenhauer

I'm new to this also, and am using a Mac 12" powerbook and an eTrex Vista. But how to download the data from the screen to my eTrex? Couple questions: Is MacGPS Pro a good program? Is another one better? Will any serial-to-USB adapter work (a little one came with my Epson printer) or do we need to buy the $50 one? Thanks. - Schopenhauer