The Shortest Version
There's not much difference between the two systems, in the grand scheme of things. Look at the exclusive games for a system, see which games on the list make you drool, and pick that one. The best models for most people are the Xbox 360 Pro and the PS3 40GB.Once you add in the cost of the Xbox 360 online service (you want the Gold pay version and not the free Silver), the prices come out the same: $400. Both systems have HDMI ports for your HD TV.
The Long Version
The differences between the two systems, graphically and so on, are relatively small. So the choice mostly comes down to other factors.
- Are you going to play online? If so, with strangers or friends? Which systems do your friends have?
- Which exclusive games make you salivate the most?
http://en.wikipedia.org/wiki/Category:PlayStation_3-only_games
http://en.wikipedia.org/wiki/Category:Xbox_360-only_games
As far as which individual model to get for each system:
Xbox 360
Don't buy a used Xbox 360; you're asking for trouble. Don't buy the bottom-of-the-line Xbox 360 (the Arcade model); it has no hard drive for downloaded games, etc.That leaves the Pro (20 GB) and Elite (120 GB) models, at $350 and $450 respectively. If you plan on making your Xbox 360 the center of your media universe and filling it with tons of movies, music, etc etc., then sure, drop the extra hundred bucks. For most people, the Pro is the better choice.
Also, factor in another $50 or so for a year of Xbox Live Gold.
PS3
Right now, the only PS3 that Sony's shipping is the 40GB ($400), which is fine and good but won't let you play PS2 games. If backwards compatibility is important, wait for June and get the 80GB bundle with Metal Gear Solid 4 and wireless DualShock 3 controller ($500):
https://www.sonystyle.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10551&storeId=10151&langId=-1&categoryId=27901
Buying a PS3 used should be OK, if it's not too beat up. The 20, 60, and 80 GB models are all backwards-compatible with PS2 games:
http://en.wikipedia.org/wiki/Ps3#Retail_configurations
Additionally, you can install a cheapish larger hard drive from Newegg or the like in a PS3 (the Xbox 360 HDs are proprietary and more expensive to replace).
The PlayStation Network is free.
Hope that helps!
Jamie