c4jjm:

While it's a *nix program, there are versions for Windows too. I just mentioned it because I was most familiar with it. There are other programs that will do the same thing. I'd imagine that since WinZIP can read tar files, that it probably has the ability to just add new/modified files to the ZIP file without reprocessing the entire thing. (Just guessing, no real knowledge of it.)

...roboticus

When your only tool is a hammer, all problems look like your thumb.