Installing mods on Vista...not showing up

[Why]

Every time I install a mod it doesn't show up in the mods folder... any ideas?
Although mentioned in the title I will mention again that I'm running Vista

[Nemo]

Make sure Vista isn't changing the file extension to .zip (they should be .sdz or .sd7)

[lurker]

Are you trying to put them in program files and not getting a UAC prompt? Then they're getting shoved into a hidden folder.