ehm not 100% shure but you can install the boot loader in the mbr and make it boot linux from the slave... but like i said im not shure.
Downloading linux depends on the distribution you want... There are many flavours of linux with their own goals and purposes.
I've used gentoo wich isn't really a beginners distro but can be installed by a beginner since the manual and support is GREAT! and it forces you to learn alot about linux and installing programs is really easy (1 command).
Mandrake, Mandriva, Fedora Debian are popular linuxxes. But if you want to use linux you don't need to install anything... Look for knoppix or any other livecd/dvd wich you can pop in your drive and boot from. It wil be a tad slow but you can get the feel of linux a bit like that.
Here is a pic of my desktop: (not so much eye candy but you can alter your window manager to your own wishes)
