"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..."