OH man i hate having to change passwords ever 90 days or whatever. They did a study where they show that changing your password ever X amount of days doesn't actually help.
"...particularly slams the common requirement that users change passwords at specified intervals. A hacker who steals your password is going to use it right away; he won't wait two months."
http://www.pcmag.com/article2/0,2817,2362692,00.asp
I think just having a good password and closing old accounts, or just verifying the email on old accounts would be best. When they make you change your password, people tend to write it down and stick it under their keyboards and that cannot be any better.
