NAV 2002 Beta works flawlessly (apart from the System Tray icon disapearring from time to time for some reason, but thats Beta for you).

The interface for NAV2002 is more XP'ish but it doesn't hog any more resources than 2001 does (I have checked on both 2K & XP RC2).

I have also been impressed by it as well in terms of loading times. Loads a bit quicker than 2001.