I used to be able to right-click on zip files and extract the directly in Window Vista.

After installation of various software, my window Vista lost this ability. It is as if it does not recognize the "zip" file extension. How can I "remap" Vista to tell it to associate file with the "zip" file extension be something that it is supposed to know how to unzip.

Install 7zip ( http://www.7zip.org ) and this open source tool will allow you to decompress zip, rar, tar, 7zip, gzip and bzip2 archives from the context menu

Yes, I'm using Zip7 now. But the thing is... My vista used to recognize zip files and open them fine without any problem. Something changed (or I installed something) and now it doesn't work. And I don't know how to change it back.

not sure about vista, but in xp i think you can solve by right clicking a zip file and selecting properties and change what it opens with. Maybe reinstalling 7zip will fix the problem?

right click your rar files and select the program that will open it from now on and make sure you select the box that makes it the default application, here's a screen shot...