Console on PC monitor

Okay, so, my TV is about to go out the window and into my mother's house 'cuz she whined enough to cajole me into giving it away to her. I was planning on buying a new TV, prefribly something better than the 20" SDTV I used to own, yet cheap (480p, to be precise), but am still looking into an alternate solution to saving those dollars:

Playing the consoles on my computer monitor. Say I want to do it. What parts and cables to I need to buy, especially to take advantage of the monitor's high resolutions? So if I want to play a 360 on my computer monitor, does that mean that it can use the high resolution pixel-real estate of the monitor, and essentially give me an HD-quality image for free? Do toss out suggestions, links, and helpful advice.

Thanks!