Personally, I am using Winzip to unzip/zip files.

Since Winzip support command line, like

WINZIP.EXE min -e -o -j c:\data\data.zip c:\

You just need to create a command button and RUN /N7 before it.
Certainly, in file section, you can find a lot of code/program for you to run DOS command line within Visual FoxPro


Hee... Hee...
After thousand of trial, I feel the winzip can be used in my application.