I have been doing some GIS noodling on my Mac recently, since it is an Air and very nice. So, what can you do without parallels on a Mac? Lots. The new QGIS with Grass plugins is great, but if you want to just get your hiking points in and overlaid on an image, you can use GPSbabel. Also free (with suggested donations though, and it is a good thing). You can download your waypoints, tracks and routes from your Garmin (I used a GPSMap 60CSx) with GPSbabel (use the GPX format) and use the GPS plugin in QGIS to easily map them. But, going the other way? that is more difficult. I used GPSbabel with csv format (x, y, id) and uploaded an important route to my Garmin. I was feeling all adventurous until a colleague sent me this link: ben sinclair's site: how to use a garmin with your mac which sorts it all out for you.