I got 12" old laptop, Asus F9 Series. It has Duo T7500 and 2GB RAM with Windows Vista Home. That is a bit old. Today, I did an upgrade. I change the RAM to 4GB. Originally, I wish to upgrade to 8GB. But the laptop only has DDR2 slots. The computer I went today has 2GB DDR2 RAM. Therefore, 4GB is the max I can have. I hope that will have good enough.
I did an OS upgrade too. I changed to use Kubuntu. That is lighter than Winodws, I think! Moreover it got more modern interface than Windows Visa.
Now, I successfully did the upgrade. The laptop is with Chrome, Mono and Java EE too! The most important is its performance is still OK!
(P.S. Kubuntu is installed successfully, all hardware drivers are working)