Many thanks. Interestingly, I checked with my dealer today, and he says that the BMW unit WILL work in the 2000 model. I questioned him on this, and he said that the techs said it would. Interesting. In any event the price is $300 (parts & labor). I am still debating, as the iTrip I purchased for $30 over the weekend is working pretty well for around the town driving. I don't normally use the BMW for trips, as it is hard to fit a wife and two boys in the 3 series; better in the Explorer. So that would mean another $200-300 to wire the Ford. Hmmmmm. maybe I'll stick with the iTrip and XM. Not being a screaming audiophile, I have a higher tolerance for not quite digital quality.
In any event, MANY, many thanks for all of this info!