Create Virtual Harddisk Using DISKPART      Open the   Elevated Command Prompt   with Administrator Privileges and type the following commands:      DISKPART   CREATE VDISK FILE="c:\win7\win7.vhd" MAXIMUM=20000 SELECT VDISK FILE="c:\win7\win7.vhd" ATTACH VDISK CREATE PARTITION PRIMARY ASSIGN LETTER=X FORMAT QUICK LABEL=Windows7 EXIT  This will create the  VHD  file of primary partition. You will see the newly attached disk in Disk Management with Drive Letter X:                      Attaching and Detaching VHD in  Windows 7     Right Click  on My Computer and Click ' Manage ' that will open up  Computer Management , in that click on  Disk Management . Just like previous part.     Then Right Click on Disk Management and select  'Attach VHD'.  This will open new windows  'Attach Virtual Hard Disk '             Click on  OK  and that will attach the existing Virtual Hard Disk. Now, if you don't want to make write anythin...