Yes, you can have 2 OS, one on each HD.
It's all about the partitions. In fact, you can even have one hard drive with 2 partitions, each having an OS.
When having a dual boot system with more than one Windows OS (95, 98, ME, XP, etc.), install XP last.
When having a dual boot system with Windows XP and Linux, check the installation instructions for the Linux distribution you are using. Usually, the Linux installation program will ''see'' that Windows XP is installed and will install Linux on a separate partition. It will also configure a menu that lets you select which OS to boot when you first turn on your computer.
Many distributions of Linux are free. Try Xandros, Ubuntu, or Suse to start. If you don't have the bandwidth to download a CD or a couple CD's worth of installation images and burn them to CD, then get a ''Linux for Dummies'' book or a Linux magazine with a CD in it. Your local big bookstore should have both.
I bought a new hard drive and my question is can i have two OS on separate hard drives Win Xp on one hard drive and linux on another?
Second question I don't know much about linux can one of you give me there official web page and how much it cost?