I personally do not pay much attention to National polls. They are meaningless because of the electoral college.
The only polls that are relevant are specific state polls. I want to know whos in the lead in PA, OH, and FL. Three critical battleground states.
I really don't care what the MA/IL people think of McCain or Obama since I know that state is assure for Obama. Same for McCain for Arizona & Utah - its locked in as Republican.
Here is my suggestion for an accurate assessment of polls:
1. Gather all swing states -
2. Examine the polls of those states
3. Add a plus/minus of the electoral votes gained/need from that state in addition to the votes from solid blue/red states.
This criteria should show you a fair assessment of what polling means in this election - not some general AP/Gallup poll.