Best software is coming with the Garmin products. City Navigator.
You can buy a USB antenna bundled with City Navigator for 149.95 Canadian $ herehttp://www.gpscentral.ca/products/garmin/18deluxe.htm
I bought City Navigator for a 276C Garmin GPS and paid $160 (just for the software) before I found GPS Central. I will buy the USB antenna for my Laptop but since I dont plan on traveling till next year I hold off on buying since CityNavigator is supposed to get an update in the near future, and if you have an older version the update would cost you around $80.
I used CityNavigator on my travels this summer in and around Calgary and never had a problem not finding an address. I talked to the people at GPS Central about software and which one to buy, they said that Garmin is defenetly the best outthere since they have the lagest selection of units and are regularly updating their software, where as others are not that quick.
I dont know how good MicroSoft system is or what mapping they use, but I know that COSTCO used to sell the USB antenna and software for around $129 Can. A little cheaper then Garmin but do you really trust something that comes from MicroSoft?