With dual boot it cannot be done. But if you install e.g. Windows 7 in a vBox virtual partition, you can switch between the 2 systems with one click. The instructions are below - allocate a maximum of 1GB of RAM to the virtual partition and 25 to 30GB of disk space (it will be allocated as used). If you have 3GB or more of RAM in your system, the host system will have no performance impact. With 2GB of RAM, you will see a certain impact.