could power chord be messing up my battery life?

I've checked everything but the power chord. Could it being so old be the reason why I can only get two hours of power out of my battery that reads to be working fine in system profiler?

15" MBP late 08 unibody, specs below.

I've power cycled my computer by taking out the battery and holding the power button for ten seconds already... seems to be calculating a longer period to charge then before... still would like to know if the power chord could effect the batter performance and whether apple can actually test to see if it's fualty.