Actually, thinking about this, you should compare apples to apples. If you take the 7mm vs the 30-06 & the 300 mag. vs. the 7mm mag. Now, more accurately, the .308 caliber beats the 7mm all around the board...
Check out these numbers:
Energy at: 100 200 300 yards
300um/180gr 3686 3201 2786 ft/lb
7mag /175gr 3187 2718 2313 ft/lb
AND you have the greater bullet selection of the .308... <img src=icon_smile_big.gif border=0 align=middle>