Two factors make this somewhat challenging aside from the expense even using an HTPC.
A. Your screen must be able to maintain polarization, and it just so happens such screens are not so great at all for 2D viewing.
B. You still can't really use just any old PJ. Many do odd things polarizing the light in at least one color before it leaves the PJ.
This is what I wanted until I really looked into it. I am just waiting for some 720p relative cheapo compatible DLP to come available. The other factor for me with it? It has to be compatible with both 3D BD and Broadcast 3D. The broadcast part is really iffy right now using an HTPC and even 3D BD hasn't really been tested on an HTPC yet as well, as far as I know anyways.
So, with dlp, you keep the screen you have, hook up your source(s), get some active glasses and your there.