How can I have two iTunes libraries on my computer(windows), for my music and my wifes?

My wife has an iPod and iPhone, I have an iPhone. Is there an easy way for me to have two separate iTunes setups on one PC. I have tried separate playlists but I have to uncheck all of the songs of hers I don’t want when I sync, then recheck them when she syncs. How can I do this and how do you switch back an forth? I know I could maybe find this other places, but I trust fellow flutherites better than strangers. Can you all help?