If you click on english bobs link and click on executables and download one of the first two pc versions of gzip. Install it somewhere on your harddisk. start winzip and drag a compressed obj or cr2 into winzip, it should (in version 8) ask you where gzip is installed, find gzip and then winzip will be able to decompress the files (you only have to point to gzip once). Version 9 of winzip is supposed to automatically handle gzip files but I havent tested that.