BleepingComputer.com: No Wi-fi

My ex-girl friend had a PC which we were able to connect to the Internet via a wi-fi system in our condo building. My PC(Windows 7-64 bit) connects to the Internet via a cable modem. I bought a router and connected the cable from the modem to the router and a cable from the router to my PC. Everything worked fine. Then we split up and I removed the router cable and plugged the cable directly into my PC from the modem. Again, no problem.
I recently bought another PC(a Netbook, like hers was) and reconnected the cables as they were before she left. But I couldn't get the cable modem to connect to the Internet. It's only when I disconnect the cable from the router that I get an Internet connection. In the Control Panel, under Network and Sharing Center, I see the Wi-fi is connected to my floor wi-fi network, but the SBN(cable modem) is X'd out.
I need to know what steps to take to connect me to both networks.

Edit: Moved topic from Web Browsing/Email and Other Internet Applications to the more appropriate forum. ~ Animal

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I suppose that you mean the modem WAN port is connected to the routers WAN port also. What router model is it and do you still have the manual?

ASUS RT-N10 EZ N Router. Only a quick start guide, which is minimally informative..

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According to the specific information found on some websites, the router has a QIS(quick internet setup guide)wizard. A browser will automatically open. Might wanna check your Internet settings for any proxy set to be able to access the setup page once the router is connected on your modem.

I found the Quick Start Guide. 1. Connect your devices (DOES THIS mean I rerun the cables for my cable modem thru the router and then to the PC? and even tho I can't get to the Internet, the browser(Google) will automatically open/launch and I just need to followe the Quick Internet Setup steps to then connect me to the Internet?
Sorry, but I'm trying to be as specific as I know how...

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Yes that is how I understand the quick setup guide also.