Cheap laptop fix: How I learned to upgrade my own RAM | Crave - CNET: It took my friend persistently reminding me that his RAM upgrade on the same laptop model (a late 2008 aluminum MacBook) paid huge dividends on performance to finally pull the trigger. I'm glad I did. Even then, I waited about six months. My computer got progressively slower with each OS X update, until Lion gave me endless spinning wheels with only one program open.
A quick search on Amazon gave me a bargain: Crucial's 4GB upgrade kit with two 2GB modules cost just $26, or $29 after tax and shipping. A no-brainer. For older laptops, getting RAM costs practically nothing at all.