Not so Rocky....
most modern XC forks are rated up to 203mm rotors. Even the lowly Rock Shox Dart 1 that is stock on the Yukon! Most modern 32mm + stanchioned forks are rated to 210mm! Fork manufacturers have started to realize that folks that are heavier than the mythical 150 to 170 ideal do ride bikes!
Anyway, to the OP. I'd deffinately check out what the manufacturer has to say about the max rotor diameter recommendation for your fork. If it's doable, I think you'd find that going to a 203mm rotor in the front and a 185mm rotor in the rear would solve your braking problems without having to resort to a complete set of new brakes. I weigh 230lbs without gear and ride an 05 Stumpjumper with avid mechanicals. 185mm rotor front and 160mm rear and the brakes have plenty of power.
Getting the parts you'd need to convert to larger rotors would run you about $115 at full retail, that's two new rotors, plus the front and rear adpaters to accomodate the larger rotor sizes. That's pretty much less than a single good hydrolic brake (front or rear) would cost you!
I'd give the larger rotor combo a try first.
Update: All 2008 Fox Forks are rated to at least a 203mm rotor. You should be good to go.
Good Dirt