I also had that question so I emailed the entertainment card co. They assured me that the 2004 card would be accepted. I ordered it yesterday for our Oct. trip. I figured if I got the 2004 card we might could go back next year. I can't wait.
Shoot, I wish this question had been posted yesterday before I ordered a 2003 and 2004 book of the site, especially since the only 2003 book not sold out that was any where close to me is 75 miles away. Oh well, at least I only paid $10.