A bit of a basic one this, so appologies in advance. Been playing consoles/pc's for 20 years, had an xbox for a couple of years. Never even considered playing online before now. Lots of chat about Halo 2 and XB Live at the moment that has stimulated an interest, soooooo what am i missing? What is the format of the play? How does it all work? Is it just one person vs another Fill me in please!