there could be a lot of things that you might need... too many to know now. other than a place to connect the power cord from the projector... id say put a really wide piece of code conduit in there, seeing as connectors such as dvi, etc. are big and bulky and cannot be easily terminated by hand (i.e. you will have to feed it terminated the whole way instead of unterminated and doing it yourself at end...)

------------------
This post has been brought to you by curegeorg, thanks for reading.