These are compressed (.zip) files which will decompress to a PDF (.pdf), for which you will need Adobe Reader which usually comes pre-installed on most computers. These are large files up of around 5 - 10 MB each, therefore a broadband connection preferable.

If you don't have the latest version of Acrobat Reader, you can download it for free here.  

You may have problems using some versions of Apple's Safari as your browser to download the magazine. Microsoft Internet Explorer or Mozilla Firefox both work fine in most versions.