If you buy a 9600 GT, 9800 GT, 9800 GTX+ or GTS 250 between July 1 and August 1 from select e-tailers, you will receive an entry code that you can use to enter the contest. In the (likely) event that you don't win the $2,400 trip, you can still use your entry code to download the complete World of Warcraft Classic PC game which you can play for free for 30 days.
If you were already planning on buying one of these cards, you might as well enter the contest and get your free 30 days of WoW. If you want to enter but you don't want to buy a video card, you can do the following:
Alternatively, you may enter this promotion by mailing the following on a piece of paper or a postcard to NVIDIA “BlizzCon 2009” Sweepstakes – Entries by Mail (USA & Canada), NVIDIA Corporation, 2701 San Tomas Expressway, Santa Clara, CA 95050, U.S.A.:
All mailed-in entries must be postmarked by 11:59:59 p.m. (PDST) on July 15, 2009 AND received by 11:59:59 p.m. (PDST) on August 1, 2009.