I haven’t seen a monitor not capable of displaying at least 720p in a long time. I’ve got a 1680x1050 widescreen dell 20" lcd, just shy of 1080p but media player does a good job of resizing.
Anyway, I don’t like watching tv on my pc monitor, it’s not comfortable sitting at my desk, and it’s too small to view from across the room, you won’t be getting the HD experience that way.
What I did is built an HTPC and hooked it up to my HD TV. At 37" it’s not very big, but fits nicely in my living room and its a lot better (and cheaper) than an equally sized PC monitor.
I’d recommend you get an HD TV (LCD or plasma) and hook up your pc to it so you can watch netflix movies, joost, tv tonic, what have you from your living room couch.