I've been using Rubitrack, and I like it, but you've got a more immediate problem. Polar doesn't make Mac driver software, which you need to get data off the device.

There's another training log called iSmartTrain, and they are the only place I've found that publishes drivers for Scandanavian HRMs (my wife has a Suunto). I'm not a big fan of their software. While they do list support for some Polar HRMs, they don't mention the one you've got—I'd suggest downloading the driver and seeing if you can get anything useful out of it. Otherwise you may be SOL.