Win7 64-bit host with a WinXP 32-bit guest
A new version of VirtualBox is out. This is essentially a mainteance release with many bugfixes (see the changelog HERE). VirtualBox 3.2.6 fixes the OpenGL support for 32-bit applications under 64-bit Windows guests.
You can download VirtualBox 3.2.6 HERE.
VirtualBox is a virtualization technology for x86 hardware. What does it mean? With VirtualBox, you can run unmodified operating systems (including all softwares installed on these operating systems) directly on top of your existing operating system, in a special environment called a virtual machine. Your physical computer is called the host, while the virtual machine is called the guest. More details in this post.