Try an easy distro like this
http://www.mandriva.com/download
It comes as a live cd. Click on live install and you will be given the option on where to install it.
I havent personally installed on second HDD but I believe it will show IDE 1 and 0 with XP on one of them. Choose to auto install on the empty drive and Mandriva will do the partitioning for you.
Importantly. when it comes to installing Grub, install that on the XP drive or you wont get the Mandriva option at boot.
If you need more advice look around here
http://www.linuxforums.org/
Other distros to pick from, and Im assuming your a newbie to Linux, are Ubuntu and SimplyMEPIS