http://www.xlr8yourmac.com/ has a lot of illustrated tutorials for hard drives and other upgrades.
Replacing RAM, hard drives and CPUs in a Mac is fairly easy -- if you decide to upgrade any of those components, we can walk you through the exact process, and if that doesn't help, we can point you to a specific illustrated document on how to do it.
Might wanna pm bobw. He's got a list of Apple service manuals, which illustrate how to upgrade/replace just about any component on Macintosh computers.