Some things I learned from putting up a drop ceiling that you might find helpful...
1) Most of the instructions/kits I have seen tell you to nail the edge rail up to the wall. This is a pain (partly because I could miss the side of a barn with an oversided hammer)...I ended up using a clutched cordless drill, a screw sleve, and drywall screws. They are quite easy to screw in using this type of setup.
2) The kits I used camed with eyes to screw into the joists to hold the drop wires. Find ones you can use with that same drill from #1 (the ones in the ArmStrong kit I bought did not have any sort of drill attachment). Home Depo carries a separate install kit which has eyes and a drill attachment together.
3) If you are special ordering tiles and have not done this before, do not underestimate the number of spare tiles you need! I have not worked with the fiberglass ones, but the regular tiles break fairly easy (I would think this is not as big a problem with fiberglass). In addition, you will likely need to recut some...there is a lot of play in the ceiling until you get the last tiles up there. I found that I needed to go back and recut one or two to get a really good fit.
4) The hardest part for us was defining the level line for putting up the railings around the room. In my house, the floor in the basement is not quite level...as such, we had to make decisions on constant drop vs. constant height. However, make sure to snap a chalk line for the rails...we did not and ended up with really a small error in our level which resulted in having to make up about a 1/2" delta in height on the last wall. However, drop ceilings hide minor errors quite well http://www.avscience.com/ubb/smile.gif
However, installing that ceiling was one of the easier home projects we have done. That room (not a theater) was about 12ish x 12ish and we (3 of us total) completed it in an afternoon without working very hard.
Hope these comments help you out.