You what to look for a Seagate ST1000LM014 SSHD You don't want the newer FireCude version! It is a fixed speed drive unlike this one which will run at the slower SATA II (3.0 Gb/s) speed your system runs at. The MacBooks 2.26GHz Intel Core 2 Duo P7550 processor is the same as the 13-inch MacBook Pro, which is to say it has less power than the previous MacBook we reviewed (2.4-GHz Intel Core 2 Duo. But we have a small wrinkle here, the drive you need is no longer being made so you'll need to look for one on eBay or Amazon. As it turns out there are hybrid drives (SSHD) which have a deep cache SSD to speed things up.
So what to do? The easiest thing here once you've maxed the physical RAM is to upgrade your drive to a larger unit. So if your system is low on free space you won't have that much space for the virtual RAM in addition over time HDD's tend to get fragmented so the free space maybe heavily scattered across the drive which slows access.
The simplest is About This Mac, available by choosing About This Mac from the Apple menu in the upper-left corner of your screen. There are several ways to help identify your Mac. When your system is running lean on RAM it will leverage the drive as virtual RAM. Use this information to find out which Mac Pro you have, and where it fits in the history of Mac Pro. This memory is compatible with 2009 Quad Core 2.66GHz/2.93GHz/3.33GHz and 8-Core 2.26GHz/2.66GHz/2.93GHz Mac Pro System. This kit contains 2 sticks of 16GB DDR3 ECC Unbuffered Memory sticks.
There is a bit of symbiosis between RAM & drives. Processor Specifications: 32GB (2X16GB) DDR3 1066MHz PC3-8500 240Pin ECC Unbuffered Memory kit for Mac Pro System 2009.