I'm looking for GPS software to use with a BU-303 when I'm on the move. I need it to have the following:

1. have maps for the UK or be able to import them
2. work with USB GPS devices that use the SIRF chipset
3. preferably give a 3D view
4. be able to plot routes and give directions

The best I've found so far is RoadMap but I've not managed to get it to compile so I can't test it. GpsDrive doesn't detect my receiver, RoadNav thinks it's disabled, some are only usably in North America. Am I really asking too much here? Anyone got any suggestions?

I can not provide much help dealing with maps or 3d view. However, according to the posted links this unit is recognized as a USB to serial adapter Prolific 2303 chipset which is well supported. The /dev/ttyUSB0 device should be automatically created when you plug the reciever into the computer. Again according to the posted links the receiver outputs NMEA0183 so it should work with most any GPS software and is listed as compatible on the gpsd website.
gpsd is the backend for gpsdrive.

So is the device being recognized?

http://www.easydevices.co.uk/pp/GPS_..._RECEIVER.html
http://mt.oisec.net/pivot/entry.php?id=17
http://gpsd.berlios.de/hardware.html

Can't say I've used it (I downloaded it at some stage and had a very quick play), but see if http://navit.sourceforge.net/ helps