1.Click your Start button and then click Run. In the text field, you will type in "cmd" The command prompt will appear.
2.Type in subst x: "C:\windows"
Replace the "x" with the drive letter for the virtual drive you want to create. This can be any letter so long as it is not assigned to any other drive on your PC.
C:\windows represents the particular directory in which you want to create your virtual drive. You may choose to create it in any directory or file on your PC.
3.Once you enter your info into the command prompt, your virtual drive will have been created. You can go to My Computer and view your new drive. However, if you shut down your PC now, it will be automatically deleted. Here's how to make it permanent: Open your notepad by clicking
Start => Programs => Accesssories => Notepad.
Next, type subst x: "C:\Windows" into your notepad. Now save the Notepad document as c:\autoexec.bat.
4.Click on Start and then Run. Next type in re-edit. Click on OK. This brings up the Registry Editor
In the left-hand side pane, click on:
My Computor => HKEY_LOCAL_MACHINE => Software => Microsoft => Windows => CurrentVersion =>Run.
5.Next, right click on the right-hand side pane. Click New. Select String Value. Now type in "Autoexec" and then click Enter.
Right click Autoexec and then click Modify.
6.Close your Registry Editor and restart your PC. And you're done!
source:www.ehow.com/how_2136865_virtual-drive.html Answered Apr, 14 2011