Should be quite do-able. Depending on which distrobution of linux you go with, it might even set everything up for you. What will probably happen is it will install onto the drive you specifiy and then, if you want to dual boot (which in this case you do) it will setup LILO (linux loader) onto your MBR. Then, when you reboot, you will be prompted as to which OS you wish to load, ms win, or linux.
As for which distro is easiest to install... probably something like mandrake, redhat, suse. Once you get going, you can play with the other distros like slackware.... mmmmm, slackware.
Good luck.