Depending on which distro you want to you, some of the more "friendly" ones (like Ubuntu/Mint) allow you to install inside Windows, by creating a bootable virtual HDD. Simply mount the ISO of the distro, and follow the prompts. I am posting this from a fresh install of Mint alongside Windows 7 - installed and setup in about half hour. I'd certainly recommend that approach if you just want to try it out, and to uninstall simply run the uninstaller from Windows.