OK, the initial download apears to work OK, the problem I'm getting is when trying to run the exe, nothing happens. I checked the file version info via right click | properties. This shows that the file was created using Power Archiver,

Downloaded the trial version of power archiver 2006
Install and run power archiver trial

From the Power Archiver application tool bar Select "file | open"
From the explorer window, navigate to the "file types" drop down menu at the bottom of the window, then select "all files" from the file type menu.

Use the power archiver's directory/drive list to Navigate to the folder you saved CS3 to.

Select the cs3 beta exe file, then click "open"

power archiver then prompts you to allow it to run the setup file that was packed in the cs3 beta archive, just cancel that, wait for it to show all the files in the cs3 archive.

From there select all files from the tool bar menu "edit" select all.

Then from the actions menu select extract, choose a folder or make a new folder to extract all the files to, then extract the contents of the cs3 beta archive to the new folder.

All the files are intact and cs3 will begin to install but I am not running a compatible OS so it say's unable to install etc.. Hope this all helps.