boot time will improve somewhat thanks to the blacks faster transfer speed (7200 rpm vs variable* rpm on the green) and larger cache. You might see a 5-6 second improvement there.
Most applications will not see much of an improvement at all.
*The green uses a variable rpm design who's top speed is 7200rpm so its not as far behind the black as many people think.
Thanks for the reply. I think I'll pass on the HDD upgrade then and be happy with what I got.