[Future Proof]

I second the recommendations concerning the 360 or PS3. The Wii is more of a social console, one of those things where you get people together and swat at tennis balls or smack gerbils around, or whatever the game may be. And when the Wii works it works quite well, but it gets largely overshadowed by the games on the 360 and PS3, especially when it comes to online play.

I recently swapped my 360 for a PS3 and couldn't be happier, though the choice was largely so that I could get on with building a blu-ray collection. Turns out though that the PS3 has got some amazing exclusive titles as of late however. Demon's Souls was an incredible adventure/RPG game with some of the most innovative online implementations in some time. Borderlands, though not a PS3 exclusive title has an awesome online co-op mode which it sounds like you'd enjoy. And Infamous, though not a multiplayer game is an incredible action title that is also a PS3 exclusive. It plays similar to Prototype (if you've checked that out already) but has a much better graphic presentation and more memorable characters. Not to knock Prototype however, nothing out there feels as visceral as Prototype's action.

But yes, I think the PS3 has got the momentuum at the moment. With most quality titles coming out for it lately and an amazing selection of exclusives, I feel that it has caught up and maybe even surpassed the 360 in terms of library quality and depth. IMHO, that happened once Demon's Souls came out because it is completely amazing and revolutionary, and that is the one title that adventure/rpg fans need to play, even if that means having to buy a PS3 to do it.