To access folder options in Vista is a bit different from that of XP.
You have to go to the control panel (switch to classic view) then select Folder Options, and the view tab, then under Advanced Settings, you can pick the options you prefer.
I don't like this way. XP was more convenient as you could change a folder view from the tool bar at the top on any folder at any time. Now you have to go back to the control panel each time a folder option needs to be changed...
Luckily I don't have to do this often but I like to see the file extensions that I am working with and I also want to see hidden files as well.