I agree with what everyone has said thus far.
LCD is the far better option, and the Sony Bravia series is essentially the best on the market today for a realistic budget.
I used to have several plasmas that I would leave on a lot, and soon had problems with severe burn in. Today, I would never go back to plasma, for that and other reasons.
Also agree with what Legend said about getting the biggest size you can afford. I originally had a 46" but soon wanted "bigger and better", so I upgraded this year to the 52" Bravia model. You wouldn't think it would be that big of a difference, but it really was night and day. I now use the old 46" in the bedroom where it works out perfectly with the room size.
If you ever need help with finding a good projector, I can help on that end as well. I use a Epson projector. Great if you are looking to create a "theater" atmosphere or just for general viewing if you can get the room dark enough and want a large/huge picture (120"+). You also have to get a decent screen in addition to the projector.