An HD TV should be 1920x1080, which is exactly the same as an HD monitor.
HD TVs will almost definitely have an HDMI connection which most modern graphics cards will also have. Alternatively a DVI to HDMI adaptor will work if your graphics card only has DVI, the signals are identical DVI just doesn't carry audio.
Older TVs are more of a gamble. CRT generally aren't worth the hassle as they're so low res.