I would get 2x 24" monitors (I actually have 3

). Exact same model and brand. You'll have 2x the screen real estate so you can browse documentation and work on stuff. You can also keep messengers, emails, tweeter and everything else up on one monitor and your work on the other. Just make sure you get 1920x1080 or 1920x1200 monitors. The bigger the dimensions (inches) the bigger you want the resolution. 1920x1200 is currently the most affordable massive resolution. The common resolution for big monitors is 1920x1080 though.
Get a monitor from LG, Hanns-G or Asus. They're all quality.
To setup multi-monitor, you video card needs to have atleast 2 outputs. Then you can just plug them in and it should autodetect. You may need to get DVI-HDMI adapters though. You also need to check the specs to see what the max resolution supported is. If it can't support 1920x1080, you should probably upgrade the video card too.
DO NOT buy a TV in place of a computer monitor! TVs were not designed to be used for reading text from for extended periods. Without doing tedious tweaking, you'll have a hard time reading and induce eye strain. I have a 55" LG TV hooked up to my computer and reading text from any distance causes a headache. We also use an HTPC and it has the same issue, text hurts.
Also, do not buy an LED or Plasma screen. Both of them have the burn-in issue. Go with LCD. If its advertised, look for an IPS LCD.