RAM for the Compaq Presario: http://amzn.to/2a2hWpO Make sure to verify application for your specific computer. Instructions on upgrading the Compaq Presario RAM
To remove and replace the hard drive on an HP Compaq Presario, all you need is a small Phillips screwdriver.
Step 1. Remove the battery.
Step 2. Remove the hard drive cover.
Step 3. Slide the hard drive so the tabs line up and you can easily pull it out of the bay, it may take some effort to slide it, it is under spring tension.
It is advised that you use an anti-static wristband when handling sensitive computer components. http://amzn.to/2a6rjGz