Service Pack installation issues

I download what I think is the correct service pack cr200_sp3_fullbuild.zip but I get and error message when I try to open it.

Window Title

Compressed (zipped) Folders Error

Content

Windows cannot open the folder.

The Compressed (zipped) Folder '......\cr2008_sp3_fullbuild.zip' is invalid.

Crystal Reports 2008 on Windows Vista.

Has anyone seen this?