Running Linux from a CD in Windows doesn't get you much closer to computing in a Windows-less world. To make Windows and Linux and either-or proposition, you have to set your PC to dual-boot. With Canonical Ltd.'s Ubuntu 7.10, a.k.a. Gutsy Gibbon, the repartitioning is done for you during installation.
Before you install Ubuntu, create a full system backup. Creating a system restore point may not be sufficient, because a misstep during installation could render Windows unbootable. Make sure that you've got your restore CD/DVD handy, and that your system is set to boot from its CD/DVD drive.
Once your backup is completed, insert the Ubuntu installation CD and restart your system. When the Ubuntu logo appears, the option to Start or Install Ubuntu will be selected. Press Enter, or wait 30 seconds for the installation to begin on its own. This runs the OS from the CD. To install it on your hard drive, double-click the Install icon in the top-left corner of the screen that appears after Ubuntu finishes loading.
The first of the seven-step installation asks you to select a language, the next to choose a location, and the third to pick your keyboard layout. Now you're ready to set your disk partitions for dual-booting. You can let Ubuntu do the partitioning by going with the Guided - resize option that's selected by default. This sets the new partition size automatically. You can also choose to set the partition sizes manually by choosing the Manual option.
Once you've set your partitions, you're given the option to migrate some of your Windows settings to Ubuntu. Select the user account, and the folders you wish to make available to your Ubuntu account (you'll also create an Ubuntu account and password to import the folders to). When the account is complete, you'll see a summary of the options you selected. Click Install to confirm the choices and begin the installation. When all the files are loaded, you'll be prompted to restart your PC.
When the PC restarts, you'll see a menu of your OS choices, one of which will be Windows. Make your selection, and get to work.
Tomorrow: Troubleshooting Ubuntu hardware glitches, and getting to know the OS's applications.