Thanks to all who have helped me with this, I've got the bug now, I love playing with the Toughbook

Loaded XP Pro SP3 (TinyXP) applied all of the drivers (and the GPS registry fix) downloaded from Panasonic (in the right order, thanks tomcat57)
Everything works as it should (so I'd be surprised if it's the cut down OS), the battery is showing (in windows) as having 4 hrs runtime on a full charge (chargecount 32 according to the battery calibration)

The only fly in the ointment is the GPS, when enabled it makes the cursor fly around the screen at random, clicking at random.
I've tried both 'Auto' and 'Enabled' in the Bios ( also tried all available IRQ under enabled ) with no effect.
I do have certain items disabled in the bios (serail port, wireless modem), I've tried various combinations with the GPS enabled but nothing works so far.
I've never seen the GPS working so I may have a faulty unit.
Any ideas? How can I test the GPS? (Do I need a Panasonic test floppy?)