Upgrade pre-RC (70xx) to RC (71xx)

use the following trick to to upgrade successfully from pre-RC (build
70xx series) to RC (possibly 71xx series).

1.Download the Windows 7 ISO.
2.Burn the Windows 7 ISO image to a DVD, and then copy and whole image
to a storage location that you wish to run the upgrade from (can be
either any directory/folder on any partition/drive on the machine
running the pre-release build, or a bootable USB/FireWire flash
drive).
Alternatively, it’s possible to directly extract the content of the
ISO to a desired folder using file extraction tool such as WinRAR.

3.Browse to the sources directory.
4.Open the file cversion.ini in a text editor such as Notepad.
5.Modify the MinClient build number to a value lower than the
down-level build. For example, change 7100 to 7000.


6.Save the file in original place and original name.
7.Start the setup process of Windows 7 as per normal from the modified
copy of the installation files, and the version check will be
bypassed