Hi RJS,
Now you say that you are new to this, now is that shooting? or just hunting?
Now until we know I will go along with the idea that your new to shooting. My advice is to steer clear of the Magnum rifles for Now! you wish to hunt Mule Deer and Elk, well my suggestion Would be bearing in mind your desire for a "flat shooitn cartridge" get a nice 30-06 and go and practice with it at the range or where ever you can shoot safely and get used to the gun and it's sights. The reason for sugesting this is that the magnum recoils more which can put off newer shooters, and even those who don't like recoil. This can also cause a flinch which once picked up is the devil to learn to lose
Best yet is if possible actually try out different rifles, like those of friends and see which you like shooting best. Magnums have their place and are fine rifles and cartridges, but in most cases are not really required for most hunting situations. I am planning an Elk hunt either next year or more likely now 2007 and I will be using either a 7.92mm (8x57mm) or a 30-06. No I am not a magnum hater
had a 300 WM in a Ruger No1, lovely rifle accurate too but I wanted a deal involving some Boer war Mausers and did not have enough cash so the Ruger got traded. The only magnum I have now is a big one, the 458 WM.
The really good thing about the 30-06 is that you can get ammo for practice at very good prices, and if it does not cost a fortune to practice, your more likely to shoot more, and if it does not belt you about, again your more likely to shoot more
The .308 would be a good choice as well. However it's your money, your shoulder and in the end your call.
Have fun and good luck with your choice