I have set up a number of clubs with projectors for karaoke/satellite/videos etc and they can be very successfuly additions but you need to make sure the picture quality is up to par and that the screen can be easily seen and readable for the majority of the customers... I have seen bad projector installs or older models where whoever is viewing the screen has to basically sit directly in front of it
customers off to even slight angles from the screen got blurry pics or distorted views... I have also seen places where the screen was at floor level, behind the dancefloor no less, and whenever even a single person or couple started dancing they were blocking the screen
a few things to think about anyways... if you can find a decent "newer" projector and screen that fits your budget then go ahead and get it... if it succeeds in filling your needs then it can be a big attraction to your existing customers and drawing in new customers... there is a place not far from me now that has a projector and they ended up painting one huge wall in the bar and project their karaoke and videos onto the whole wall... it actually works out very well and they have it positioned high enough on the wall that even someone 6FT won't block the view... good luck- tig