Agreed. Nutrition is first on my list. I'm not gonna kill myself with the P90X. There are easier schedules to start out with, and I did it just fine last year, but you're right. Definitely don't want to burn out.
I have to concur with the burnout from p90x. The time commitment is what got to me and I only was able to get to 60-70 days before I had to start skipping days because other things were coming up ( and once I skip a day of anything its usually all down hill from there). While an hour and half is not that much out of your day, it does really restrict when you are going to do other things... I wish I could just wake up early and work out.