http://www.xbconnect.com
play xbox live games right now. plenty of gamers & games supported. well-respected, reliable and FREE. you use your PC w/ XBC installed to trick your xbox into thinking it's on a LAN. it will system link flawlessly. takes less than 2 minutes to setup. and you can voxchat using Skype.
but I recommend also getting XboxLive, it's so cheap and worth it for the amount of free content downloads, etc. and if you haven't already, pick up Halo, Mech Assault and Crimson Skies. all very cheap. and Halo2, MA2 are coming out soon so you'll be ready. most XBL games are compatible w/ XBC. However, Halo is not XBL compatible but will work on XBC and worth every penny.
if you want cheap xbox games, visit ebgames.com website every morning before 9am and sort by lowest price.
new
used
their used games are high quality and come with cases/instructions and guaranteed to work. and everything can be returned in store, buy prices online are cheaper. nearly same price as renting. plus they always have huge coupon codes for used games floating around (15-30% off)
if you've never played these, they are worth the coin:
Tom Clancy's Splinter Cell - Pre-Played $5.99 (not xbl)
Star Wars / Tetris Online Disc - Pre-Played $10(xbl/c) (2 games)
Deus Ex: Invisible War NEW $10 (used is $18)
Legacy of Kain: Defiance NEW $10 (used is $18)
STEEL BATTALION ($200 MECH game plus 40 button controller + foot pedals)
http://www.ebgames.com/ebx/product/227919.asp
also check out
www.cheapassgamer.com and
www.vgtalk.com for daily discounts sent in by members. the deals do not last long. have fun.