what you want to de does not really make sence unless you limit the first sorting.
if you have ,say 500 files, sort them first for number playes, and then randomnize them, they will end up just as random as without the sorting.
but, you can for instance say
sort for number plays
limit the sorting to for instance 250 files
and then sort random
this is more or less how a lot of my smart lists work.
in your case it should be the other way around
first sort random
then limit (when you want all songs in your library included take a large ammount of items)
then sort for number plays
the limit is used to 'fool' mc a bit.
gab
edit... now for the limit, you could for instance also put a limit advanced there with
-1,10,[number plays]
wich will give you only 10 songs per number plays. or you could make something that it will only select one track per album
just an idea