so you're looking to replace your current monitor or to get the second one?
as far as TV vs monitor goes, I'd surrender in favor on monitor any day. (reason being I was in the same boat once and got a TV to serve as well TV and second monitor. worked out as it was decent for TV but was quite crappy for a monitor. Now, I may defer to the fact that maybe the TV wasn't very good, it was one of the early models, etc but generally I believe that picture sharpness is a lot better on monitors than on TVs of the same size)
that said, however, one thing to consider is that typically monitors come with 1 port for each interface (VGA, HDMI, DVI and DP). A TV would be more likely to come with several HDMI ports.
monitor with speakers has HDMI and DVI vs TV with 2 HDMI
if you got a separate sound for computer, then you can go with monitor and use DVI to hook up the computer input and HDMI to hook up the xbox. However, if you want to use the new monitor as source for sound from both computer and xbox a TV would be a better solution since DVI does not carry audio signal. (there's options to get around that but it's another story)
Just something for you to think about in logistics terms besides just picking out which got better quality/picture/refresh rate.
Well, my current monitor uses dvi. I wasn't thinking of getting a second one, maybe use a monitor or tv with hdmi to use the xbox and pc instead of having to go to the living room to play xbox and back to the computer room to play on the pc.
For audio I have the chimaera 5.1 from razer. I have to change the optical cable everytime I use the xbox (no big deal there). Unless I get a TV with optical out. At the moment when I'm going to play on the xbox I have to unplug the headsets and take the whole thing to the entertainment center, then back to the pc when I'm going to play or watch movies.
What drew my attention to tv's was to connect both the pc and xbox to hdmi and use the optical out for the headsets. But I've been reading a lot on the internet that tv for pc displays text horribly and all sorts of problems with browsers having to zoom to be able to display content.