I'm going to stick with 2006 for another year. They don't do enough from year to year to warrant buying the game annually. Hopefully by 2008 they'll have some idea how to make a salary cap work or how to do player progression in their Franchise mode. In my franchise now, I have the best team in the NFL every season and I'm always 20 million dollars UNDER the cap. Managing the salary cap should be THE challenge in franchise mode.
It would also help if the other teams in the franchise mode did things that made sense. Teams will literally spend their first round pick on a QB every year. A few years into my franchise, I noticed the Texans had 5 QBs on the roster.
I'll get Madden next year for PS3 or the Nintendo Wii (when, ideally, I will own one of those systems).