What are some opinions of the "service plan" warranty's being pushed by the electronics stores? Most people I talk to seem to buy them and they are convinced the projection tv's must be cleaned once per year (at $150 a pop). What is actually done in a cleaning? I am looking to buy a Panasonic 53" ws around Christmas for around $1700 but the store where I am purchasing wants another $400 for the service plan. This adds roughly another 25% to the buying price and makes the deal seem not-so-great. I have been burned by the "service plan" before but I have never owned a projection TV.