aechelon & awwaiid: I can't seem to hold back the pulseaudio packages, too many Squeeze apps depend on the .21 libraries. I wouldn't be surprised if my hack (swapping in some of the .15 client libraries) is causing the problem.

megaexer: If you are getting 404 errors, it means you need to download the package list again. You can do this from Synaptic by choosing Edit -> Reload Package Information.

I'm going to start adding these things to the wiki when I can. I just added the above advice to "Installing Applications".