Even if you don't plan on using an Armstrong ceiling product, their website is worth a visit if you are considering a new acoustical ceiling. They have great information of installation of suspended ceilings, tile ceilings (tongue-and-groove squares without a suspension grid), and planks... the acoustical ceiling wood wannabe!!
Armstrong also has an online calculator that will compute the amount of materials needed for any suspended ceiling job... http://www.armstrong.com/resceilingsna/index.jsp
AND WHILE YOU'RE AT IT... The ACE HARDWARE website has a fine tutorial on
suspended ceiling installation... amazingly missing from the ARMSTRONG site
(though, to be fair, ARMSTRONG does include useful and complete instructions
with each box of ceiling tiles).
Product and installation information on both suspended and staple-up ceilings, from one of the leading manufacturers, as well as info on their other building and renovation products. Wallboard and plaster are also covered.