A few points
This isn't meant to be a declaration or war, nor a replacement as it instructs Bush to go after anyone responsible in anyway not just official governments.
It is the job of Congress to approve of Presidential military action after 3 days of deployment by the President as instructed in the War Powers Act.
Congress is not the commander in chief nor can they dictate the president's every action and they are not meant to. It is the president's job to defend this country, Congress is meant to supervise and act as a check through powers of financing military action and impeachment.
Constitutionally, Congress should declare war if we are in a conflict against another nation, but today's gov't sees very little point in that as it limits the President in how far he can go as listed in the Declaration and who he is suppose to attack.
This is very different from the Iraq Resolution in that it instructs Bush to attack the people that attacked us already as well as the wide variety of people that are involved rather than one nation where a declaration of war is more appropriate.
In all of this, Congress has little power in containing the President from attacking another country and completely wrecking it short of impeachment, even without this resolution, Bush could have attacked all of Afghanistan and impeachment would have been very unlikely with the amount of popular support he had.