The readme.htm file is at http://www.microsoft.com/downloads/details.aspx?FamilyId=E1E22BEC-A937-4E09-A16A-2FD69D711053&displaylang=en

The trial edition download is at http://www.microsoft.com/downloads/details.aspx?familyid=7de00386-893d-4142-a778-992b69d482ad&displaylang=en

 Or you can get the trial bits directly at http://download.microsoft.com/download/f/7/6/f76437c4-6e3d-4618-94c9-3bff8141bee0/VSTSDBTR.img

If you are an MSDN subscriber log in and you'll see DB Pro as an available download!