If you did not yet notice: There is a new feature in Windows 8 concerning disk images. Instead of using third-party software for it, you can now mount .iso files and more with a native Mount function. To access it,
How to enable Windows 7 Aero in Virtualbox
If you try to install a Windows 7 system in a Virtualbox you will notice that there is no 3D support there - no feature of Aero works and the Desktop is shown in the Aero fallback mode without transparency.
Mount disk images in Windows 8
Windows 8 introduces a new feature concerning disks and virtual drives: it is now possible to mount disk images via explorer without using third party applications such as Daemon Tools that create virtual disk drives to be able to use