Change default memberlist order to top posters

[boatdesign]

Currently when you visit memberlist.php you get an alphabetical display.

How difficult would it be to change memberlist.php so the default display (without passing parameters to it) would be by the number of posts (top posters)?

First I think this rewards those who are most active instead of those who simply begin with the letter A. Second it might help reduce the spam signups who sign up with a name like !!!-00-aa-spam in order to get to the top of the memberlist