RIGGS,
You do have a "system", but you really need to open up a Statistics book and find out what "standard deviation" and "margin of error" is.
I am not getting on you, but:
Is the power rating a forcaster of future performance or a grading of past performance?
A power rating simply tells you how a team has done - and not what it will do. I think the trick is in figuring out which team has a power rating that is way below/above what it should be - that is where you get value.
If you think a certain team has a low power rating because they missed their PG for a few games (Phoenix Suns) or because they just overlooked a few teams, you might want to play them.
If you think a team has a high power rating simply because they played a schedule filled with home games (West Virginia, Syracuse), then you might want to consider going against them.
The trick is not is USING these ratings to forecast the games, but in identifying where the ratings are wrong, or where the ratings have overlooked something that you think is very important.