Is there a difference between a home theater projector and a power point projector?

I will be giving a talk to about 150 people and thought it would be nice to use my word perfect presentation program to prepare some slides. Last time I used a slide projector but I'd like to jump into the computer age this time. Problem is, I don't know anything about projectors. Do all laptops support the kind of projector I need? Do the projectors have different ports? How about the lap-tops, do they have varying ports? Is one cable better than another? How come some projectors are $400 and others are $1200? As you can see help is needed.