Removing 16000 zip extentions from directory?

i've downloaded a shareware game and when i extracted the rar file , i've find a weird problem : all files have a zip extension, i scanned the file and i've not found any virus so i want to remove the zip extension from all 16000 files so please help me to do this!!

thanks in advance for your help

Select all files and... ... 650ei7.png

ImageShack is down for me at the moment, so he's a locally hosted screenshot of what I think AlbatorIV's would be, in case it's down for you as well: