First know that DLP & LCD are two different technologies. DLP uses a single mirrored chip that reflect light through a color wheel while LCD uses 3 chips that light passes through, one for red, green, and blue.
DLP can cause the rainbow effect, but if you don't see it, then don't worry about it. DLP typically has a higher contrast ratio than LCD and produces much better black levels.
LCD is typically a little less expensive, though this is equaling out but it never can have a rainbow effect.
Drawback to both?
Both types are little projectors mounted inside a cabinet. Projectors have bulbs and bulbs burn out. Sometimes they last several thousand hours, sometimes they don't. Sometimes they blow out after 1,000 hours or less than half a year after you get it if you watch regularly.
Replacement bulb: $300-$500
Do some math and ask about guarantees and bulb life PRIOR to puchasing a rear format projection televsion over plasma. I got a plasma because I didn't want to deal with bulbs and the life of the plasma is about 10 years. I will replace it by then, or delegate it elsewhere in my home.
Read this article
http://www.projectorcentral.com/replacement_lamps.htm
It was written for overhead front projectors, but also applies to rear projection technology and is something to consider before you buy.
There are 4 dominating THIN big screen technologies (and a few smaller ones) - Rear screen projection LCD, rear screen projection DLP, plasma flat panel display, and LCD flat panel display. If given the budget, many people would get the LCD flat panel display from Sharp which is 45 inches.
The king of quality is still the big rear projection CRT display though. If you have the room for it, you get a better price and higher quality with no bulbs to replace and about a ten year life span - or more - from rear projection CRT.
Lots of choices, lots of advantages and disadvantages to each - the choice is, in the end, your to make based on knowing the quality, size, initial cost, and cost to maintain factors.
