Which version of Vista are you running? What security software are you running - the Microsoft trial, or some other security software, like Symantec or CA?
I have installed LDW's version of the game from both an admin account and a standard account (using my administrator password), and the game runs fine for me on Home Premium.
I have home basic with Microsoft trial...
I'm still convinced it's because of the two files that I can't delete in program files. It's just too much of a coincidence that when I try to download, that that's the two files that it can't download...Maybe I need to call Vista?
I appreciate all you're trying to do though...