Goodness, glancing at the list of updates below, I may have to upgrade. If you rely on a local update server, you will need to update to the latest version as well. Details on that can be found on the Altium Designer 6 - Local Update Server Setup page.
The following updates were tested against the standard installer, which means that you should have no problems applying the update. If you have any concerns, have the back up performed on the machine with the existing version of the software. Remove the existing version prior to installing the update. You can determine if you have the latest version of the software by going to Help | About.
The.zip file is not torrented, it just compressed. As such, it cannot be downloaded by the popular torrent sites such as deviousdude86's dl directory or bownload.com by the same person. Windows 7 (.zip) is a perfectly valid file, as is WinRAR, but the better tool to use is 7-Zip or similar. The reason I am telling you about this is that it allows you to download the file in chunks. If you are a programmer, you may already have 7-Zip installed. 7211a4ac4a