Here are the links to the most commonly asked questions and their answers for QuarkXPress 7.x/8 in general:
(if you look for specifics for PDF creation, Printing etc., please consult the specific forum)
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Operating System / Platform Support
Does QuarkXPress run on Leopard (Mac OS X 10.5)?
http://forums.quark.com/p/7627/32041.aspx#32041
Does QuarkXPress run on Windows Vista?
http://forums.quark.com/p/14218/58401.aspx#58401
Does QuarkXPress run on Snow Leopard (Mac OS X 10.6)?
http://forums.quark.com/t/21811.aspx
Does QuarkXPress run on Windows 7?
http://forums.quark.com/t/21811.aspx
What's the difference between QuarkXPress 8 and QuarkXPress 8 Plus Editions?
http://forums.quark.com/t/20346.aspx#81579
Installing
Can I install QuarkXPress 6, 7 and 8 at the same time (on the same machine)?
http://forums.quark.com/p/7861/33134.aspx#33134 and
http://forums.quark.com/t/21675.aspx#87368
When I try to activate QuarkXPress 7 or 8 it crashes. What should I do?
http://forums.quark.com/p/22639/91458.aspx#91458
Opening & Saving
How do I downsave to 6 (from 7)? (Same for downsaving 8 to 7)
http://forums.quark.com/p/7588/31906.aspx#31906
Why does a document downsaved from 7 not open in QuarkXPress 6?
http://forums.quark.com/p/7997/33782.aspx#33782
How do I reduce the file size of QuarkXPress documents?
http://forums.quark.com/p/7272/30513.aspx#30513
Preferences
Where are the preferences stored and what's the story about the preference folder location?
http://forums.quark.com/p/19198/76668.aspx#76711
Importing pictures or text
I seem to not be able to import XTG (XTags) anymore?
http://forums.quark.com/p/6775/28368.aspx#28368
How does QuarkXPress integrate with Photoshop, Illustrator or other creative apps? And are there tips & tricks on the integration?
http://forums.quark.com/p/16374/68606.aspx#68606
Documentation
Where do I find the keyboard commands (PDF) for QuarkXPress 8 referenced on the CD?
http://8.quark.com/documentation.html
Troubleshooting / Crashes
What's the latest version of QuarkXPress I can update to?
http://forums.quark.com/t/7648.aspx
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Whenever there's other topics that you want to see get added here, feel free to tell me (by hitting the Contact button above this mail).
You might also want to consult our virtual knowledge base: http://dynamicpublishing.quark.com/support/knowledge_center.html
Enjoy!
Matthias