SuperOneClick is a free Android device rooting software for Windows and Linux, developed by XDA Developers.
SuperOneClick features an easy to use rooting application for most Android handset models. Just download the program, put your phone in USB debugging mode and plug it in. Users are also insisted to unmount their SD card first before rooting with the program.
Once you've rooted, you can continue as normal to install apps, and even install customs game ROMs to get the most out of your phone.