When we designed the new BitWise IM site, we re-confirmed our choice to use buttons for the program downloads instead of links, because buttons both look better and say "press here" better than any text link. Yet, as always, when problems arise, we listen.
We received an inquiry over the weekend from a user who was unable to download a new version of the software because the button system wasn't working, supposedly due to high security settings. It also wasn't unheard of for some browsers to have problems with downloads from forms (*cough cough* Mac IE *cough cough*) so on the download page there is now a link to show text links instead of buttons for the downloads.
Technology may not always work the way we expect, and the same techniques may not be foolproof in all circumstances, but generally most problems can be overcome with a combination of methods. It's too bad that most places don't take the time to figure it out.
Why not just a text link near the button? Or be fancy, and have the button overlap a text link via CSS, and thus when it fails to load (say, via a high security setting), the underlying link will instead be present. Tis an idea.