i no longer unnecessarily maximise windows, so i tend to keep my desktop clean as a result. My downloads folder is another story. i used Belvedere for a while when it was in alpha, but stopped using it when i realised that as a Vista user, i could just use smart folders.
What's this and how do I use it?
As usual, when it comes to usability, Microsoft is like a GAFer talking to a girl -- clueless, while Apple is the Mac. (

) If they were smart, they'd actually call them something like Smart Folders, so maybe people would think something along the lines of iTunes' Smart Playlists, but they're either inept or dodging antitrust charges. Actually, IIRC they were called Virtual Folders in the beta. They're called Smart Searches in the final release.
Basically, anytime you perform a search, you have the option to save the search. This is the "Smart Folder". The searches are normally save in the \[user name]\Searches folder, but you can drag the search to where ever you want it. If you hit Win + F, it'll load the search tool which will let you create your own custom searches. For instance, all of my downloads hit a central download folder. i have a search that finds files in that folder and finds AVI and MP4 files over 500MB called "Movies". The files don't physically move. All you're really doing is filtering the results of the search. But it's a very useful ability given the pretty robust Vista search engine.
Again, if Microsoft were smart, they'd have the option for creating a new Smart Folder right under the regular folder. Then it launch a wizard to select what criteria the smart folder would look for, and you'd be on your way.
If you want to see all the criteria you can assign to a Vista search, check this out:
http://windowsvistablog.com/blogs/windowsvista/pages/advanced-search-techniques.aspx