Read the in-dept article: http://e39source.com/archives/797
Upgrading BMW E38, E39, E46 and E53 GPS Navigation hardware. In this video: upgrading a February, 2000 E39 M5 from a MKII computer and 4:3 display to a MKIV and 16:9 display. Parts are best found on eBay. Installation is fairly simple, just takes some time to bypass the tremble hardware if you’re migrating from an MKI or MKII to an MKIII or MKIV computer.