WinZip v. StuffIt
WinZip is well known as the standard file compression program. But for a long time it has had a less known competitor which may be superior. Consider downloading StuffIt:
StuffIt gives you the option to compress files in the .zip format, and if you do there will not be much difference from compressed files created with WinZip. However if you select .sitx format you should see a noticeable improvement in the compression size. I just tested compressing 27 files (a mixture of Adobe PDF, PowerPoint, Excel, and Word files) totaling 70.1 MB in WinZip and StuffIt. The zip file created by WinZip came to 58.4 MB. The .sitx file created by StuffIt was 52.8 MB. Not an insignificant difference.