Ok, if you want to use it as a TV as well then get the >=42" but it's not ideal for what you stated below imo.

Here's why...

HD TV currently has a maximum resolution of 1920x1080! Not bad for a computer screen also but think how you work; you'll have your master document open which you need to type in (or paste too in my case ) and you'll have several other documents/web pages open to research from. How would you position all your windows, firstly you would have to always drag them accordingly with the master one in the middle and several others either side. Not a problem with 1920 horizontal? hardly, you'll run out of real estate on your desktop in no time.

Now with just three 24" wide screen monitors each at 1920x1200 you not only already have more real estate per screen but have the ability to have your primary screen in the middle for your master, just maximise the page and you'll easily be able to edit at 2 full pages on the screen ;then the other two screens can be your reference screens either side for research material. You can still drag windows from one to the other of course and even drag maximise to the full 5760 horizontal!!! if you had too!

Now that's going for the latest hi-res widescreen monitors but I do the same at home with just two 19" widescreens running at 1440x900 each and I would still get more space than one large flat panel TV hybrid! It works for me as I have my document open on one screen and typically browsers on the other when I am referencing.

You must have a few monitors at home and a couple of graphics cards, try adding them all to one system and you'll soon see where I am trying to lead you and I can guarantee you'll find it hard to move back to a single screen, whatever size as you'll miss it badly!