Not bad for just eyeballing it... Although I used to be able to do cubed roots to some number of decimal places in my head, for some reason I always have trouble getting triptychs properly measured and aligned. I am sure there are some sort of actions, but I rarely do those,so I have not looked. :-)

As for the frame, I really like "Mikes Framer" for CS3/CS4. He charges something minimal like $6 but it does a lot. (A lot of really cheesy stuff too, but the good stuff actually looks good) You might want to check out his plugin.
http://homepage.ntlworld.com/pooternerds/Framer/index.html