For RA3 the key should be at HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Electronic Arts\Electronic Arts\Red Alert 3. If you don't have that key, it might be best to just reinstall to the new drive as you will be missing other keys as well.
Yea, that wasn't there for some reason and manually adding the keys doesn't help. So, I just reinstalled the game and all is well now.
Thanks for everything guys!!