The chipset itself has busses to main memory, AGP, PCI etc, with the memory bus speed determined by the chipset.
The latest and most popular GPS chipset used not only in Bluetooth receivers for cell phones and PDAs, but also in standalone and car-mounted navigation units is what is known as SiRFStar III, sometimes simply referred to as SiRF III.
You need fast, large hard disks, lots of processing power, and a good motherboard and chipset.