All puns aside (I'd go for the 30 min one):
Get the 2.8GHz MBP. In gaming you want the most possible, video editing and encoding are hard hitters on the processor. Also, since you have a 5-year old PB, then its logical for you to want to have this new MBP for another 5 years. So, to a 5 year outlook, I'd say future proof it as much as possible and a 2.8GHz CPU is a good way to future proof your new baby.
Other than that, I rest my case.
But be aware that the quality of the current hardware is far, very far away from you powerbook I wouldn't plan the expense on a 5-year period.