Plasmas don't last long - a few years of you're lucky, they are very delicate and get damaged easily. LCDs are good for large screens, have good picture quality and last for 10 years plus (this is info from an expert and from my own personal experience - not the 10 years bit obviously!)
Personally, I have a 32 inch cheapo LCD, as well as a 40 inch cheapo LCD - had them for 1 and 3 years each - the picture quality is excellent. Previously, I would never but anything but Sony, but now I will never buy a 'premium' brand again!