Never heard of Aviton before, but it looks like you can get a refurbished TomTom for the same price, which would probably be a better idea.

http://www.tomtom.com/products/product.php?ID=702&Category=15&Lid=4

You typically don't need any software to use an gps in car navigation device, they tend to be pretty much standalone units (though you can usually upgrade their software, upload new maps and load points of interest data to them via a computer and the software the gps manufacturer supplies).