Can my boss cancel my vacation time (approved seven months prior) at the last minute?

Let me preface this by saying that I'm a huge sports fan, and a season ticket holder for the Washington Redskins. When the football schedule came out in April, I saw that we had a Monday nighter on November 3 against the Steelers. I immediately requested vacation time on Nov. 3 & 4, and it was immediately approved. I found out last week that the final copy of our budget for 2009 is probably going to be due that week. While my boss isn't the type to ask someone to cancel their vacation and he hasn't mentioned it to me, I'm a little afraid that this could become an issue. First of all, does anyone know what (if any) rights I have as an employee if this situation arises? Secondly, does my boss have the right to scrutinize over the fact that I'm not taking the vacation time to go out of town (it's not as if working those days would require me to cancel hotel/flight plans)? I value my job, but I also firmly believe that companies shouldn't run our lives.