We hunt with 30-06s, I've seen and know people who hunt with nearly every common caliber out there and if they place their shot right, it is dead.
Where you are hunting maybe important as well. I mean if you want to take long ass shots you may want to invest in a higher end rifle and a caliber that is prove to have a decent trajectory. All my hunting is 150-200 yards, more like 100 yards or less though usually.
Also a big lesson I learned recently is the scope is as important as the rifle - if not more important. Unless of course you're just going to use sights.
My '03 Sold.