I originally had an upgraded 640GB western digital blue hdd and 4Gb of Ram (back in 2009) but it was getting really slow.
I performed the blackmagic speed test and was only getting like 75/Mbs Read/Write.
So I purchased a samsung 840 250GB SSD, 8Gb Ram from crucial and the data doubler from OWC.
There were a lot a videos on how to install everything on the OWC site. (Or check their youtube channel)
So now I have an 880GB fusion drive that reads about 280 MB/s and writes about 240 Mbs (My 2009 macbook pro is only SATA II so it's capped at 300 MB/s and the Samsung write speed is capped at 250 MB/s.
So I increased read speeds almost 4x and write speeds over 3x and now my macbook pro is a snappy little beast once again. (Still not as fast as my 2012 11" air but still pretty fast)
Since I contemplated selling the 2009 macbook I thought I would share my story and mention that it was an easy process and really breathed some new life into my old macbook.