I have a 21 inch CRT monitor that I use for LFS when I want to drive during the day and I have a Sanyo Z3 high definition projector that I use at night which gives me an image of about 110" although you can have a much bigger image (or smaller) if you're space allows. The only downside with projectors is that they need to be used in a light controlled enviroment as heavy sunlight will make your image look washed out and I don't really like sitting like a vampire with all the curtains closed during the day if I want a racing session.
LCD monitors are good, but for a large one you will pay almost the same as what you would for a HD projector. If I had to choose between the 2 I would go for the projector as the experience is much more immersive when playing on such a large screen.