Set your NAT type, to "open".
you dont
Yes, Halo 3 supports multiplayer Xbox Live gaming for any one with an internet connection and a xbox live Gold account
Halo Wars does have Xbox live.
Get better internet.
Halo is only on the Xbox or the Xbox live.
Over XBOX Live and through Local Connection (2 XBOX 360's linked up with eachother)
When you boot up Halo 3 go to the main menu, then choose matchmaking, but make sure you have Xbox Live connection, and there you have it, online multiplayer.
yes the halo maps are free on xbox live.
no, you must connect to xbox live to download halo 3 map packs.
Yes. An Xbox Live Gold Subscription is required to play Halo 3's multiplayer.
No, you do not need Xbox LIVE to play any original Xbox games. Not all original Xbox games can be played, but Halo and Halo 2 do not need LIVE to be played on the Xbox 360. I just now tried it with my LIVE unplugged and signed in to an offline account and it let me play both of them. The previous answer was a lie, obviously.
You do NOT need Xbox live to play Halo Wars. Xbox live is only used if you want to play with other people and to update the game.