Steps By Steps Windows Installation Method
Click start. Right-click Computer in the Start Menu and then select Manage. Right-click Computer. Click Manage. Click Disk Management under the heading titled Storage on the left of the window. Click "create and format hard disk partitions". Look for a new window to appear titled "disk manager".
Select your C drive within disk manager. Right click on the C drive and choose shrink volume. Wait for the new window to appear after it is done calculating. Look at the screen asking you how much you want to shrink the drive. Enter in 30000 to shrink it by 30gb. This will leave you 30gb for Vista, and 30gb for windows 7 new computer installation. Click shrink to continue with the process.
Once complete right click on the new partition in disk manager and select "new simple volume". Look for the new window titled "new simple volume wizard" press next and keep the size that is pre-filled in for you. Click next again. It will ask you for the drive letter, keep this as D or whatever letter it has assigned, note this drive letter down for a future step. Click next.
Click the radio button "format this drive with the following settings. Make sure it is set for "ntfs" as the file system, "default" for allocation size unit, in anytime windows repair is required, Volume label can be named anything you want. Make sure to check mark "quick format"; press next, and then finish. Press start in Vista then "my computer" you should now see a new drive number.
Restart with your Windows 7 in computer installation disc and choose custom installation once the screen is shown. Choose your new drive as the install drive. Once installed you will now have the option upon booting to go into Vista or Windows 7!