Microsoft do an Autoroute package, including USB GPS dongle for £149 retail. It was in the PC World sale at £99. Not sure about changing voices though.
Tom Tom sat nav has changable voices, although the 'official' tomtom voice range is pretty poor, with John Cleese being the only 'celebrity' voice available.
There are however, a range of 'non-official' voives for tomtom including, Patrick Stewart (Captain Picard), Ozzy Osbourne (bleeped and not bleeped), yoda, arnie etc. The quality of the impressions ranges from very good to "Who the hell was that supposed to be!....."