I use winrar do unzip my files. Basically I run it in Admin and open a zip. Select the folder of the mod you want.
Drag the mod folder from zip to the paste location either;
C:\Program Files\Ubisoft\SilentHunterIII\DATA or MODs
Its should merge the files.
If you get access denied then you are only a user with limited access to the root hardrive and Vista is very picky.
Make sure your user level is admin. Should work I never had your problem unless I try using a program to save in the game folder. Vista doesn't allow that. You have to save your Zips in \User\Downloads\ then extracted it to abc.
You should only turn off UAC if your the only user on the pc. Anyhow if you deactivate the UAC you might have to reinstall most of your programs if not a clean install. Program in the changed regestry may not work after off switch!
