RIM has apparently discontinued download and support for all versions of it's BlackBerry Desktop Software version previous to version 6.1, currently available at this link.
I've archived previous versions here if anyone needs:
I down loaded the files. Nothing newer than 5.01 will run on my windows vista computer. Version 7 won't run either. At all. It won't even start, it shuts down as soon as I click it or connect my blackberry. 5.01 b080 works fine.