Ok, If you guys are having so much trouble over this, Just set up a maximum character count on sigs, so you dont have to worry about the people "abiding by the rule," its forced.
I can fit exactly 150 characters on every line on my resolution. Decide on what resolution you want to go buy, count how many fit, and multiply it by 5, theres your max lol
Edit: Actually, As a matter of fact.... I believe you can simply block the maximum # of lines as well... Its been a while Since I ran a VB
but I know you can set blocks like that. (David can atleast, don't know how many privledges he gives mods)