CAnt find design premium CS3 on download page?

if you follow all 7 steps, you can download a trial via one of the links on this page using a browser that accepts cookies: http://prodesigntools.com/download-adobe-cs4-and-cs3-free-trials-here.html

and activate with your serial number.

if you have a download problem (eg, you see an error page or you are offered an incorrect version), you probably didn't follow all 7 steps.  typically, failure to meticulously follow steps 1,2 and/or 3 is the problem, but your browser must also allow cookies so that (a restrictive browser setting) is another potential source of problems.