Howdy,
ZA force install Microsoft Visual C++ 2008 run-time without checking if it's already installed or not, that's not problem as long as you include the latest version of Microsoft Visual C++ 2008 with your new installers.
I just downloaded ZA Free latest version and it installed Microsoft Visual C++ 2008 version 9.0.30729 while latest version is 9.0.30729.6161.
Search on Microsoft and you'll find the newer version and you may include that one in your next installers.
Cheers.