You have a 4.0 and 29 on the ACT but you will have taken 6 AP classes? How many AP classes does your school offer (how much you challenged yourself within the context of what was available to you is more important than an absolute comparison of you vs. someone else in terms of academic course rigor.)
Your EC's are okay, IMHO, but not spectacular (neither were mine - I'm just saying, though...)
Study for the SAT/ACT - scores won't get you in, but I think in this case they can work to keep you out. ED1 will be your best bet. Fall 2009 Vandy accepted over 45% of it ED1 applicants according to the undergraduate admissions blog:
Office of Undergraduate Admissions Blog | Vanderbilt University | Nashville Tennessee