Newer "flat screen" TV's don't have any problems with artifacting or ghosting as the older ones did. A good solid brand such as samsung or sony will do you well. For that size, I would recommend an LCD TV. Its too small for DLP (which are cheaper) and the prices start in good comparison to plasma (although plasma gets alot cheaper as you get bigger).
LCD TV's are lighter, thinner, use less energy and produce less heat (people that worry about electric cost and stuff thats nice to know) than plasma. The main problem with them is "artifcating" at higher speed graphics. Most LCD TV's (non generic brands) today easily have a 8 ms refresh rate or less, which virtually elimates this problem. Plasma's have "ghosting" and burn-in problems but, again, are alot better than a year before. Plasmas tend to be thicker, heavier, use alot more energy and produce more heat, but are cheaper.
Also, from direct personal experience, the cabling is EVERYTHING. I had a very good quality HDMI cable for my TV that my dog chewed up. I got a cheaper brand to save some bucks, and instantly I had some artifacting problems. My advice, spend the extra bucks and get monster component cables or any other good brand. With good cables and a good brand TV, you won't have any problems.
Monster Componet Cables + Samsung LCD HD TV and no atifcating playing the Wii at all.
P.S. - if you really want to save money, 720p could save a couple hundred. Current usage of 1080p are HD DVD & Blu Ray devices (includes xbox and ps3). If you don't plan to invest in any of those items anytime soon and need to save, go with 720p