I generally find it's just easier to let the individual programs set up those associations. The whole reason the program you're talking about exists, is because Microsoft was found guilty of abusing it's monopoly market position. Of course the settlement phase didn't happen until after Clinton was out of office and Bush took over, so Microsoft got away with barely a slap on the wrist. Namely, they included that little program, buried quite deep so few people will ever find it, and it really doesn't do much of anything.
So the moral of the story is, just let the programs themselves fight it out for which one gets control of certain content.
I have noticed that I cannot change "Set Program Access and Computer Default" under "Custom". It always goes back to "Use my current media player" (or whatever it is). Is there a reason for this behaviour?
Thanks in advance,