does anyone know how to set file associations in Vista?

[Gary Schnabl]

Control Panel > Default Programs > Set Associations is supposed to do 
it. However, there are a number of file associations that simply won't 
change, including .pdf or some other common types. It's irksome.

I can then browse to the desired exe and select it in order to change 
the previous default. However, that new application won't show up in the 
pane for alternative apps. And I often log in as an administrator, or 
otherwise seemingly have sufficient user privileges. Apparently not...

Gary