Check it out: http://store.steampowered.com/
It's good, it's like xfire (do you have xfire?), but it's much better than that and it's also basically a game center, you can buy and download the games (you need steam for Empire Total War and Shogun 2). It's awesome.
Just download and install it and I'm sure you will get to liking it. You can add your friends to there and chat, just like xfire.
If you have xfire, what is your username so that I can add you to mine?