I'm also having problems downloading programs off of the Internet and installing them on VISTA Ultimate 32-bit and VISTA Ultimate 64-bit. I've tried running the programs as an Administrator, and everything else that I can think of.
I even swapped out the Motherboard. In the end, I gave up, and called Microsoft Support. I had to pay $60. This was a week and a half ago. It seems that some systems will not allow programs to be installed if they are downloaded from the Internet. They have no known fix
, and "are working on it". I just can't wait until this hits the news. An OS that doesn't allow you to install programs off of the Internet.
I believe it has something to do with either the authentication by VISTA, or VISTA corrupts the downloaded program. If you d/l the program on another laptop, put it on a USB drive (or a CD/DVD), it will install from there.