The problem with using TVs as monitors is that none of them (at a "reasonable" price) support a higher resolution than 1920x1080 (1080p), which is worse than a standard 24" LCD monitor (1920x1200). When you're trying to fit multiple windows in 1920x1080, you run out of viewable space quick. Just because it's larger in inches doesn't mean it holds more discrete pixels. The only upgrade in my view to a 24-28" 1920x1200 monitor for multiboxing multiple windows is a 30" 2560x1600 monitor.

(A 42" TV at 6-8 feet away isn't going to look much bigger than a 24" monitor 2 feet away, and the 24" will be clearer when reading small text.)