For the newest Windows 7 compatible version, go to our downloads page and simply download the latest version and use your same license key:
http://www.celestron.com/c3/downloads.php
For the old version, if you get the message "ERROR NexRemote is not allowed to run on WinNTx Setup Aborted" when trying to install NexRemote on a Windows 7 machine, try setting the compatibility mode for the Operating system’s installer to Windows XP 32-bit.
This should allow you to install NexRemote, which is compatible with 32-bit Windows XP and Vista systems.