Look here for help on the xbox live test if anything fails on ya. Taken from xbox.com.
Network Adapter- If you dont have your network set up correctly-
Adapter help
Wireless Network- Tells whether your using a wired or wireless connection.
IP address fails- Xbox isn't getting a connection from your computer-IP help
Dns fails- DNS addresses are not correct, cannot contact DNS server-DNS help
MTU fails- Your mtu settings have changed or are not correct to begin with, xbox live requires a MTU speed of 1354 to run XBL. 1500 is as high as you can get your MTU- MTU help
ICMP fails- This test evaluates how your router or gateway will respond to a particular type of Internet Control Message Protocol (ICMP) packet. ICMP help
XBox live test fails-Verifys that your console has connection to XBL, usually fixed by powercycling and trying again- Live test help
NAT-This test indicates the type of Network Address Translation (NAT) that your router or gateway is using: Open, Moderate or Strict.NAT help
If you need more help feel free to post and ask questions..