Was trying to find information regarding the RAM for my particular model of G4 Powerbook because I planned to upgrade the puny amount of RAM (512MB in total, 256MB soldered) that came with the machine, and happened on the following DIY sites. Very helpful, I must say. As an example, here are illustrated guides for upgrading the RAM.
An excellent 3-part series on the boot up process of modern day computers, focusing on “Linux, Windows, and Intel processors.” Very worthwhile reading.
Recently, I was helping someone to upgrade her Mac - not that I am an expert by the way, but simply because I have been using a Powerbook (yes, the obsolete machines… 
) for the past year and have taken more interest in Macs consequently. The following are some resources I found, which hopefully can help others from getting lost in the updating/upgrading maze.
After hearing some rather worrying tell-tale sounds* coming from my PC last night - specifically, from the harddisk with the Windows operating system - I quickly made up my mind to replace it today. After all, the said harddisk is about 3 years old. Unlike all the problems I had in the past when hardware failure always occurred at the wrong time, hopefully I am doing the right thing to head off any impending problems. It goes without saying that I then spent the rest of the day reinstalling all my softwares…
New acquisitions: