Hi jac,
Welcome to Laptop GPS World.
I like the form factor of these USB GPS units. Especially for a tablet PC or a UMPC, these dongles look attractive, because there is no long cable hanging between the GPS receiver and the PC.
However, several people, who have used various GPS units with this form factor, have reported issues getting a usable GPS fix while the GPS receiver was plugged directly to their laptop. There may be some interference when a GPS receiver is in very close proximity to a laptop. When a USB extension is used, it should work fine.