as this seems to be a reoccuring topic: Mac OS X
The first version that supported Mac OS X 10.5 (Leopard) was QuarkXPress 7.31.
The first version that supported Mac OS X 10.6 (Snow Leopard) was QuarkXPress 8.1.
The first version that supported Mac OS X 10.7 (Lion) was QuarkXPress 9.1.
Please note that Lion was the first version of OS X that didn't support Rosetta
anymore, so that means that any non-MacIntel-native applications won't work. So QuarkXPress 6.52 (and before) will not run on Lion, you either need to stay on previous versions of OS X or might have to consider upgrading to QuarkXPress 9.
Please note that QuarkXPress 8.5 was the last version of QuarkXPress that supported PowerPC-based Macs. Windows
The first version that supported Windows Vista was QuarkXPress 7.3.
QuarkXPress 7.31 (and higher) was certified
on Windows Vista.
The first version that supported Windows 7 was QuarkXPress 8.12.
QuarkXPress 8.12 (and higher) was certified
on Windows 7.
versions of QuarkXPress (e.g. 7.2, 7.01, 6.52, 5.01 etc.) are not
supported on Leopard, Snow Leopard, Lion, Vista or Windows 7. "Not supported" means it may run but Quark didn't test it and doesn't offer technical support to make these combinations run. If you need help from Quark's free technical support, you need to run a supported platform.
Matthias P.S.: Info about QuarkXPress 8 & 9 & 10 here: viewtopic.php?f=14&t=4608