Just to comment on the InDesign vs. Quark speed issue.
You have to remember that InDesign is going to be slower than Quark because its doing much more work than Quark does. First, it's rendering all the Postscript and PDF to the screen, this takes CPU cycles. Anti-aliasing, multi-line composer, drop-shadows, feathering etc.. all take computing horsepower.
Quark is fast because its not doing anywhere near as much fancy typesetting and graphics processing. Essentially all the code in Quark regardless of what version is pre-System7 days and was written at a time of limited horsepower (8Mhz machines) and RAM capacities. Also, Mac OS 9 is not a true multi-tasking OS, the front-most app gets most of the CPU cycles.
Anyhow, the main issue here is that InDesign was designed for the complicated typesetting that current design standards demand combined with the move to PDF-based workflows. Quark is still living in 1989 and are dragging their feet. The totally blew it with version5 and their sales figures are certainly showing that fact (they are not a publicly traded company so those details will never be known but it doesn't take a rocket scientist to deduce this).
Also, the fact that Apple has basically deep-sixed Mac OS 9 and new machines next year will no longer boot directly into it spells disaster for companies looking to purchase new equipment in that time frame (either by choice or not). They won't have a choice, the machines will boot into Mac OS X and they will either: 1. Move to InDesign 2. Live with Quark in Classic
Moving to PC is not a real option. Think about it. if you move to PC and stay with Quark you still need to buy a whole new version of Quark (and don't tell me they give you a big break on the pricing, you better than that) and all of the plug-ins will need PC equivalents (if they even exist). Most of people who complain about moving off og Quark use the plug-ins excuse (I'll have to buy all new version for InDesign). What they don't realize is most of the plug-ins they rely upon for Quark have equivalent features in InDesign built-in.
My opinion is that moving to InDesign from a financial point-of-view is less expensive and puts you into a better position technology-wise in case your old PowerMac 9500 dies and you decide to buy a new PowerMac G(x)...
Better safe than sorry...