I have to say the biggest advantage of a console is not having to worry about whether your system can handle a game - since the games are designed to run with what the console has. Sure you won't get graphics that are as good as if you ran the game on Ultra-high settings on a PC, but that doesn't mean they'll look bad at all.

I have a PS3 myself and i'd recommend that you buy that 40gb model and then later purchase and install a bigger hard drive. Should wind up being cheaper.
And don't let yourself be swayed by any xbox fanboys out there :P
One of the biggest arguments they usually put forward is the controllers - i.e. "Xbox controller are more betterers!!1!11one1!"
This doesn't matter anymore because even if you find yourself liking the xbox controller better, i've seen PS3 controllers with an Xbox controller design floating around in electronics stores :P