I think you are right, you should go to an LCD. And because I am such a nice guy, I will be willing to swap you my 37" LCD for your 55" LCD projection; because I'm such a nice guy.
Is LCD better? Sure. But how much would a ~55" LCD cost you? Well this
52" LCD will set you back $7000
So, a $200 bulb every 2 years over the 6 year primary lifespan on the TV will cost you $400, giving you a net price of $2100 for your purchase. (My math based on you replacing it once in 2009, then again in 2011.)
Don't get me wrong, I love my LCD TV. But I can see it getting demoted to the bedroom soon and my buying a bigger TV for the living room.