I second getting a Bluetooth GPS receiver (not sure that a USB one will work) from
BuyGPSNow. I have bought 2 or 3 from them and never had any issues. I would recommend the Holux brand, the others that I have tried seemed to take longer to acquire lock (on cold start) but other than that they work.
Here is the link for discount codes
AXgps for 10% off gps hardware
AX10 for 10% off software
AX5 for 5% off gps bundles
And you dont have to be a Aximsite member