gentle persons,
as mentioned on the versiontracker, displayed by the installer, and readable in the included readme - for using xdrawchem you need an EXISTING installation of trolltech's QT C++ framework (version 3 or higher; THIS IS NOT QUICKTIME) on your computer. Use the link provided on versiontracker in "product requirements" of xdrawchem to download an installer of it. That's it. xdrawchem 1.9.2 runs happy on all flavours of MacOSX 10.3 if your computer system complies to this prerequisite.