You can use either:
WinRAR
http://www.rarlab.com/download.htm
or
http://www.7-zip.org/download.html
Both are superior to Winzip and are similar programs. WinRAR is shareware (Everytime you run it, there will be a nag window that tells you to pay money, but the program is still fully usable.) while 7zip is freeware.