Very simple - purchase a bluetooth GPS receiver (SiRFstarIII chipset, which will lock onto sat's quicker) and Navigation software. There are many different makers of satnav software out there you could try mysatnav.ie or Expansys.ie for options. Ensure whatever Satnav you choose has 100% mapping of Ireland, if your intention to use here. You may also need an SD storage card to hold maps.
Good hunting
Eoin
No link to any companies mentioned.