Steve,
If you want SAT-NAV take a pass on the unit that was offered for the 07 and 08 US models. There were a lot of people on other forums who didn't like the unit for a multitude of reasons. You could probably order one through VW and it maybe almost as expensive as ordering one of the new RNS-510 units. This unit can be is far better than the first nav unit but is not exactly a drop in unit. Mechanicaaly it fits perfectly but requires some minor programming using VAG-COM to get all functions working. The RNS-510 from VW is aroung $2,000. The older nav unit may be avaialable through E-bay. I don't know if it is a plug and play replacement. I have not read anywhere about anyone retrofitting one. Most people opt for an aftermarket unit such as Pioneer or Kenwood. If you want to do this yourself you could order your unit from Crutchfield which is supposed to have pretty good tech support and will match up all the pieces you will need. You could also see if you can find a good installer in your area. The Zenec is not available in the US as far as I can tell. Also regardless of what you get, you will need the antenna for the SAT-NAV. On the Eos, all antennas are built into the trunklid. If you didn't order the sat SAT-NAV initially, then the antenna was never installed and it cannot be retrofitted. You would have to order a complete trunklid with that antenna built in.