The Set Up
I'm going to cover how we set up our Xbox 360's in this part (hence the subheading). If you're not into all that techie stuff you can skip to the list o' games, if you haven't already. You won't hurt my feelings, I promise. I was an English major in college, so if this all reads like a bunch of uninformed B.S., ya caught me. Call the geek police.
This is how I did it. You can see pictures of my consoles here. Please, feel free to (constructively) add to the conversation in the comments section! This set up is for consoles in two different rooms. You could put both the consoles and TV's next to each other, if your significant other doesn't mind the living room looking like a frat house. I'll toss some Amazon.com links in here and there. That way I'm helping the site. Yay, I'm helping!
Xbox 360 Wireless Adapter If you're thinking of picking up an older Xbox 360 and placing it in a separate room from your internet connection, you'll need one of these bad boys. If you decide to throw down on the Xbox 360 Slim, good news, WiFi is already built in. You could always run a cable through the middle of your house, if you're some sort of uncouth squatter. They're going for about $65 bucks. The adapter, not the squatter.
D-Link DIR-655 Extreme N Gigabit Wireless Router (Almost) any router will (probably) work. We picked up this one because it has "extreme" in the title. We drink a lot of Mountain Dew. It blasts internet juice all over the house, wirelessly connecting two laptops and the second Xbox 360 to the interwebs. (Our main console is directly wired to the router.) This will cost you $70 clams.
Xbox Live Gold Membership You'll need two of these if you both want to play online. The best way to handle this is to get the Xbox LIVE Gold Family Pack through Xbox LIVE. For $100 bucks you get FOUR memberships. A solo membership is $60 dollars. I'll let you do the math.