Have you tryed the winzip website.    go to www.winzip.com ; there is a free trial verson you can download.   but its just as good as the real thing   and its free.  you never have to pay for it and it never disapears from your system.  its what i use.  i dont think you can unzip multipal files at once  but you can extract them to where ever they need to go without leaving the main folder that your in.

hope this helps.