I think its Vista's Data Execution Prevention (DEP) feature thats interfering with your installs. To turn that off, you must run the command prompt as administrator and run this command:

bcdedit.exe /set {current} nx AlwaysOff

You should see a message that says wether it worked or not. If it did, reboot Vista and Maya should install normally. If you want to turn it back on afterwards, do the same thing as before but type this instead:

bcdedit.exe /set {current} nx AlwaysOn