Hmm.. Undelphix is only a good choice when you are allready using it in your game/application.

You could try this one:

http://www.delphizip.org/

Or this one:

http://www.dellapasqua.com/delphizlib/

Or check a few of these:

http://www.torry.net/pages.php?s=99

Hope this helps.