The downloads page you are speaking about is here:http://www.sinsofasolarempire.com/update.aspx
The "Download Updates" button in Sins simply calls an "Impulse.exe" file in your Sins installation folder. If you do not have Impulse installed, it will call up the web page I listed above. If you do have Impulse installed, then it links to the Impulse executable, and brings that up.
As of now you the only option for downloading the pdfs and music files (for CE customers) is from the web site I listed above.