http://www.ubuntulinux.org/Download iso file and install to CD, then boot to CD and run without installing (you'll see the menu items first). This is called Ubuntu Live CD. I'm actually running that right now on a P4-3GHz-2MB RAM. All apps and Firefox are included. You can try it, see if everything functions and then install it on your current computer. It is quite a bit different from Windows, but not all that difficult to navigate.