This is a loaded question, but one of the key elements you will have to control is your lighting as projectors don't work too well in bright sunlight.
Fortunately, living in Canada means that for a good part of the year, it gets dark and stays dark for a long period of time. Still, you will want to look at ways to control the lighting in your basement either with dark shutters or curtains or blinds.
Other things that will play a part in your home theatre design include:
o what you will project on -- wall or screen?
o what are the acoustics in your room?
o what are the dimensions of your room?
o what are the components in your system?
It is a lot of fun, and the end result is totally worth it if you are a movie nut like me. But my advice is to take your time and invest in quality parts over time. I built up my system gradually, piece by piece, and I'm glad I did it that way because it gives you the time to learn and do research, in order to pick the best parts for your personal system.
