If you use Parallels Desktop to manage your Garmin GPS, this may set you free from Windoze altogether. After a few downloads and a two hour map conversion process, I can manage my GPS on my MacBook.
You will need three software packages;
1. The POI Loader for Mac released on Dec 19th and no longer in beta. Not required but nice to have.
2. MapInstall for Mac, also released on Dec 19th.
3. MapConverter for Windows released on September 18th.
Instructions for using MapConverter are here (pdf).
The map conversion process can take quite a while. I converted three Garmin Mapping products in a bit over two hours on my Parallels/MacBook. An external drive helped simplify the process."