I upgraded my MBP(2.4GHz Intel Core 2 Duo ) to 4GB with 2 X 2GB Kingston DDR2-SDRAM, PC2-5300, 667 MHz, 200 pins (S$55/2GB). As per David mentioned, very simple job, "nothing of a rocket science here. Just be gentle on the operation...."
If you still not sure how to do it, you can just...