I installed 8GB (2x4GB) in my 2ghz core duo A1278 and changed the 160GB Hard drive to a momentus hybrid 500Gb and the laptop was screaming fast in comparision to the pre-updates system.
It identifies ALL 8GBof memory and it runs statistical analysis regressions faster than my Quad core i-7 920 running at 2.8GHZby a factor of about 6-10 times.
I ran all the database and merging processes on the i-7 then ported the data out to the macbook to run the regressions. I couldn't believe the performance difference between the two systems. The i-7 has 12GB ddr3 1600mhz memory and 7200 rpm drives.
So yes the upgrades to the mac book were worth the investment.
Only thing faster is current generation processors (>2.5Ghz i-5/i-7) with full SSD drives.