On the off-chance you don't have a game to play this weekend, here comes Valve Software to the rescue: this morning they opened up access to the demo of Left 4 Dead to those who pre-ordered the zombie shooter.

Pre-ordering the game through Gamestop or Steam will get your access to the demo, in addition to a $5 discount off the retail price. The Xbox 360 demo went live around 6 AM EST while the PC demo went up at 9 AM.

The demo allows you to try out the first two levels of the Hospital campaign in four-player online and off-line coop modes. Unfortunately, the Versus Mode - in which four extra players play "bosses" of the Infected and hunt the Survivors - won't be included in the demo. Guess they don't want to give too much away for free.

Those who didn't pre-order the game will get their hands on the demo on November 11th. Left 4 Dead will hit stores on November 18th.