The main difference between HDTVs and PC monitors, at least that I've noticed, is color, brightness, and internal scaling (usually converting 1080i to 720p and vice versa). This applies to both ends of the spectrum. The cheaper (Westinghouse) HDTV's boast great specs, but in reality have HORRIBLE color, brightness uniformity, viewing angle, etc.. don't believe me? Go to your local Best Buy and watch one next to one of those pretty Sharp or Sony XBR 1080p screens. You'll quickly see what I mean.
If you're gonna go HDTV, don't short change yourself on the Westinghouse. Save up your $$ and go for the higher end 1080p lcd HDTVs (SONY XBR2 Bravia 40" 1080p looks incredible). Or be patient and wait til later in 2007 when the Laser HDTV's hit. (boasting better brightness and color fidelity than plasma for less cost).
Otherwise I'd just get a good widescreen pc monitor. I own a Samsung 244t (24" 1920x1200 res). For overall picture, color, and contrast, I highly recommend it. I haven't had any bad issues in games whatsoever, just a beautiful picture without ghosting.