It is possible to run OS/2 in a virtual machine on Windows 7 but the configuration you need is not one that Microsoft supports and you need to disable the block they put in place in order to allow it. You can't run OS/2 on the supported Virtual PC on Windows 7 because that version doesn't provide access to the regular drives from within the virtual machine as there's no way to run the add-on needed to implement that access.
So to be able to run OS/2 on Windows 7 you need to install the old Virtual PC 2007 instead of the one that Microsoft does support on Windows 7. So the first step is to go to the Microsoft Download Center and download a copy of Virtual PC 2007.
When you try to install this version you may get a compatibility warning and the install process will be blocked. You will get this warning if you have previously installed the Windows Virtual PC (the latest virtual PC for Windows 7 that doesn't allow access to drives outside of the VM when running OS/2).
To uninstall Windows Virtual PC go into the Control Panel and in the Programs category select "Turn Windows features on and off". Scroll down to find the entry for "Windows Virtual PC" and clear the checkbox. You will then need to reboot the computer for Windows to apply the necessary changes.
With Windows Virtual PC removed you will then be able to install Microsoft Virtual PC 2007 which will allow you to install OS/2 and have it able to access drives shared with Windows 7.
This article written by Stephen Chapman, Felgall Pty Ltd.