Yes, it's fairly simply. If you already have Nav in your 2000, then you will need the DVD Computer, 16x9 nav screen and a trim bezel. Lots have done the upgrade, do a search on this forum.
Also read up at www.bimmernav.com. There is a group buy on this board under the E39 groups buys forum and one at http://www.bimmerboard.com/forums/posts/74970. Both of these get you the screen and computer at a significant discount. Bimmer nav will have the part number for the 16x9 bezel you'll need to complete the install.