Yes, some models are louder than others, but I'm not sure I'd attribute that to DLP versus LCD. I would think that has more to do with the cooling system and the enclosure.
Now, to the original poster, if money is a concern and you want to focus your funds on the actual PJ, keep in mind that you can easily construct your own screen. There is a separate forum over at the AVS forums that deals with this. It is simply a matter of building a sturdy frame and then stretching a specific type of fabric over it, much like black-out cloth used in drapes. Just something to think about along w/ the ton of stuff we've hit u with so far. I couldn't see spending upwards of $500 to $1K on a screen. In the end, my screen cost me maybe $100 and it looks fantastic.
