Networking confuses me :(

I’m having it up to here with networking right now. Not the interpersonal kind of networking that gets you jobs and things, though I have issues with that as well; the computer kind.

My laptop has a wireless connection to the internet via the cable modems scattered throughout the apartment complex. I can connect my Xbox360 (yes, I bought one) to my laptop via an ethernet cable, which works fine for sharing media between the two (i.e., I can play songs and stuff from my computer through the Xbox360 and thus through my stereo system). It seems to me that I should thus be able to get to the internet from the Xbox360 to take advantage of the Xbox Live stuff, right? Wrong. I figured maybe I had to tell my laptop to share the internet connection, so I went into network connections and did that, but I get an error message saying that there’s an IP address conflict.

I’ve tried Googling the error message, and everything I get has to do with messing with the router. But I don’t HAVE a router. I don’t have a working modem. (I’m not leeching, if that’s what you’re thinking; the apartment complex pays for everyone’s internet, so it doesn’t matter who connects to which modem throughout the complex.) So I can’t do that.

Really bringing this to a head was my desire to poke around on the Xbox website, but they won’t even let me IN unless I sign in with my gamertag. Problem being that I signed up for Xbox Live about two and a half years ago, and apparently that was before the one time my credit card went missing and I got a new one, so it won’t recognize that I’m me (because you have to give the last four digits to identify yourself when you forget your password, which I also did). Helpfully, it says that I can find out the information I used to sign up by signing into Xbox Live on my console. Which I CAN’T DO, because I can’t get it to connect to the internet.

So, someone who knows more about networking than I do, is there any way to fix this in my current setup? Or do I need to try AGAIN to get Time Warner to fix my modem (something I have tried to do unsuccessfully, and it was an incredibly painful phone call just trying to get someone who knew what the hell they were talking about, and even then, as afore mentioned, it was unsuccessful).