There's a 7-day free trial for ISBoxer; if you're comparing multiboxing software there's no reason not to try it and see if it's worth it to you.
EVE players so far are liking this idea for multiple monitors and ISBoxer:
http://www.dual-boxing.com/showthread.php?t=41982 - and with this method it doesn't matter that your monitors are different sizes, because they're both actually on monitor 1 and at the same resolution.
I just started up my 3rd account tonight, also got my wife playing a trial now ;)