How do I improve my performance of my MBP (2009) after upgrading to 10.8.2
I have the same MacBook Pro model.

Upgrading your RAM to 8 GB will help a lot, as the others suggested. You might also look into adding an SSD using something like the Data Doubler by Other World Computing (macsales.com).

Then you could do something cool like this: http://reviews.cnet.com/8301-13727_7-57550128-263/how-to-make-a-custom-corestorage-drive-in-os-x/