It is easy, there are instructions here: http://www.ehow.com/how_895_install-ram.html

A defrag is a good idea, but you can also clear out programs that are running in the background that you don't need. Go to Start > Run > and type in msconfig and press enter. Choose the Startup tab. Look up all the checked items in Google to decide whether you need them or not. Do remember that things like Quick Time and iTunes are not necessary unless you're running the program, so shut those off. Ditto for MSN Messenger, and any MS Works items. You can turn these item on later if you'd like. When you restart your computer, choose 'Don't Show Again' to the message that will pop up. If you've never done this before, this will clear up a lot of RAM to use. Leave the non-Startup tabs alone, though!