Yup the satnav was CD based up to late 2000, then DVD based from there on. The DVD based system has a few more features and obviously covers a much wider area (like most of Europe), but the basics of the two systems are about the same.
The cost of the satnav new is around £2,400 so expect it to hike the price an extra grand or thereabouts, on a 2-3yr old car. Can't say I've seen many other satnav units, but the Lexus one is reckoned to be one of the best available (shame it can't be retro-fitted).
To be honest tho, unless you're a travelling salesman, I'd go for an IS without satnav and spend the extra on a lower mileage/younger model (or a few mods after getting it!) :winky: