If you have windows XP64 DO NOT DELETE SDCENTRAL as impulse will not let you download or update TOA saying your operating system is not compatable with this game
Or you could just run it in compatibility mode and skip the melodrama.
I'm going to edit the original post to include these instructions for if you failed to update:
If SDC is showing the latest version installed but your titlescreen does not say the correct version, or you have missing strings, etc, you can either try re-installing or you can edit the registry to force it to re-update.
Here are instructions on how to edit the version string in the registry:
First, close Stardock Central. Go to Start->Run and type in regedit. On Vista, type it in the search box. As soon as the registry opens, click on the My Computer icon and choose File->Export to backup the registry.
The install info for GalCiv2 is under HKEY_LOCAL_MACHINE, in the path Software\Stardock\Drengin.net\GalCiv2\Twilight.
Just change the version string to a lower number and when you restart SDC, it should show the update button again.
Here are instructions to make sure that you get the latest version once you've either re-installed or changed the version string in the registry:
Befiore installing the update, go to Tools->Settings and click on Internet. US-1 is usually the best choice for servers because sometimes we have sync errors with US-2. Click Refresh XML Data. Also, if you have the setting turned off to check for updates to Stardock Central, turn it back on and then re-start Stardock Central. If Stardock Central finds an update, let it update then restart SDC when prompted.