"With just over four weeks until launch, Left 4 Dead is showing every sign of topping The Orange Box on both the PC and Xbox 360, at retail as well as on Steam," said Valve marketing VP Doug Lombardi in a press release.
For those resisting the PC incarnation of the run-away-from-zombies shooter, the Xbox 360 version will hit retail on the same day. The 10% discount also applies to pre-purchase customers at retail outlets, according to Valve's press release.
"Our pre-sell numbers at retail have jumped to over 65% greater than Orange Box at the same proximity to launch," Lombardi continued. "We're seeing tremendous enthusiasm for the product in what promises to be another great year for gaming on both platforms," he added.
For the full press release straight from Valve, read on.