Mr. 4500 RPM:
Are you still looking for a flat panel?
Here's what I've found in my research and my experience in selling them for a living in the past:
Right now, as we speak, LCD is the king. This is a blanket statement that seems to not be challenged, at least at the moment. For 40"-46", an LCD will serve your needs best, IMO. Once you get bigger then that, an LCD starts to lose its edge in both price and performance.
Not just any LCD, BTW. At this size, you'll want a 1080P version, which stands for Progressive. This means that at any time, 1080 lines of picture (or close to it) will be visible on the screen. An LCD is a non-scanning type of television. See, the old Cathode Ray Tube (CRT) TV's and their projection variants were scanning type, and thus were known as Interlaced designs. That means they produced pictures in 1/60th's of a second, jumping from the odd lines (1,3,5, etc.) to even lines (2,4,6, etc.) and back and forth very quickly, at the same speed as our power lines produce AC power (60hz, approx.) They did this for obsolete reasons today, since today's panels can continuously display an image on each pixel, so Progressive is the way to go today.
The reason you'll want a 1080P vs. a 720P version at this size (40"+) is for the gaming you'll be doing, and for the fact that this won't be a small TV. Simply put, if you take a certain size of TV, and see it in 720 pixel line variant vs. 1080 pixel line variant, you'll see a big difference in the size of the pixels. This closer arrangement of pixels within the 1080P gives you more fidelity and detail with programs (like the PS3, Xbox 360) that can produce it. Regular programs look good too because the processor within the TV and/or the TV's signal producer (like a DVD or Sat. Box) will upscale a lesser image to the TV's native (or natural pixel arrangement) state. In this case, More is Usually Better, provided the price is right.
The other things to look for besides pixel count (1080P being the king right now) is contrast, black level detail, refresh rate, and color accuracy, amongst many other things. This is merely my opinion, but typically the downfall of most LCD's is that they refresh their picture slowly, so things look blurred at faster rates of speed (like video games or action movies), and the dark detail is also a problem. Contrast and dark detail faults (which plague most of the cheaper brands!) make dark, scary parts of a movie, or subtle details of a video game look flat, lifeless, and weak. Essentially the tiny things that make a shadow look like a shadow instead of a TV just being turned off are missing, and that can kill the experience of watching movies like this. To fight this issue, when shopping for an LCD pay attention to the contrast level (but avoid inflated, fake values) and look at the detail during a presentation at the store. If the darks just kinda fade into nothingness, then look elsewhere. But if you can make out detail within dark features, keep looking.
The next thing to work out is how the contrast levels and color detail make color look. Is it Real looking? Or do you have a sense of watching cartoon colors even while watching a movie, or while watching a news broadcast? Color is tough for an LCD, so finding the right one is tough as well.
Now, Here's what I'd shop for if I were in your shoes (and I recently was!)...
There is a 46" Mitsubishi LCD that is rare, yet special as hell. If you can get one, you'll probably be very pleased. I forget the model number at the moment, but it was a STEAL at Circuit city. I don't condone shopping at the CC (used to work there back in the younger days), but it was a deal worth buying (I think it was a $1100 when the TV costs realistically $2500.)
Another heavy hitter is the magic Samsung brand line. A 46" will run a bit more then some brands, but they have figured out how to get contrast just right, as well as get the color detail near perfect. Not everybody loves them, but I do. In my opinion, Sony can't even compare with today's Samsungs. That is saying something.
With those two options, you should be quite happy with your results.
My last suggestion is for you to make sure you have set aside (or may already have invested in) a nice sound system complimentary to the TV you have in mind. The audio matters more then the picture, in most cases, and these new TV's simply can't compete with a quality system. If you need guidance on audio, just ask!