Some of the more useful featurs are ClearType for users of laptops and those with LCD screens; what it more or less does is triple the horizontal resolution of the screen, improving image quality. It also allows multiple users to be logged into the same computer at once, you can switch between users without affecting the programs running in the other users session. Another nice feature is that Whistler manages dll's, so there will be fewer conflicts with software overwriting dll's with different version; compatibility issues caused by dll issues should dissapear. It also supports a better method of application compatibility than the crappy apcomat tool that is found with Win2k. There is also going to be 64 bit versions of professional, server, and adv. server for the Itanium processor.