splitting itunes

I have a bunch of music saved on my mac book pro's hard drive and a bunch saved on an external hard drive that i took from my old computer. Right now i have all the music from my internal hard drive in my itunes. I would like to add the music on my external drive to itunes but make it so that it is completely seperate from what i already have. Like having a completely different itunes for each. Is this possible? how do i do it?

Thanks

Yes.

When you open iTunes hold down the OPTION key. iTunes will give you the option to open your existing Library, Create a New One or Quit. Select to Create a new one and add the desired music.

Unfortunately there is no way to switch between the two while iTunes is running so each time you open iTunes you'll have to select a Library by holding down the OPTION key and manually selecting the library you want. when you want to switch, you have to close iTunes and then reopen it.