VirtualBox 1.5

Virtualbox is a freeware virtualization solution from Innotek. It enables the user to run many operating systems (each one called the "guest" OS) right within the Virtualbox application installed in your "real" OS (also called the "host" OS).

Virtualbox emulates all the components of the guest OS, including hardware (as VMWare does), which runs in a separate context of the host OS. However if we need interconnection with the host, it is possible through shared folders and the network connection too.

This complete virtualization avoids possible compatibility problems derived from the virtualization itself. But it means also higher system resources needed to run the virtual machine (you need a fast computer to run decently a modern OS).
VirtualBox can create virtual machines for OSes from Windows 3.1 to Vista, and also DOS, OS/2 Warp, Linux, Solaris, Netware, FreeBSD and OpenBSD.

With Virtualbox, you can access another OS without the need of rebooting the PC, with the capability of taking 'snapshots' (like restore points). Moreover, you can configure the emulation for the CD-ROM, Floppy, Sound driver, Network and USB, define shared folders and a remote screen.