Um, you realize this is late for me and it's my day to sleep in tomorrow...
Anyway, I've got no idea what Quark is. Running Classic isn't a problem though. We had an old iMac die on us (hard disc is just not spinning) and have had to press my (sob) iBook into service as the Airport software base station (we don't have the Airport base station hardware thingy). Because of the stupid adsl connection software, it has to be in Classic mode. It does just fine. It boots up in Classic (ie OS 9.x) and goes from there. I can still get to OSX (by rebooting) if, say, I need some data from my account on there (eg an email address). My husband even resurrected one of our old computers (an old iBook) to run OSX. It runs beautifully.
I hated the beta version of OSX. It crashed and was a pain. The finished version is lovely, though. I especially like the "Terminal" app where you can pop into Unix and do whatever .. for me, not so good in Unix, it means that I can kill any application giving me trouble. Die IE! Die Navigator! It's kind of fun, sometimes. Really, you have to use it to love it. It's much much better than 9.x in terms of stability, I think and the GUI is just one of those things you get used to. Once you get used to it, it's much better. Plus, you can still get to Classic mode, so you haven't lost all your most loved apps.
Have I raved about Airport yet? I love sitting out in the garden looking at email and reading mumsnet. No reason not to have Airport.
I have the feeling that the Tech is sitting there and laughing at me. Well, let it be said that I'm the one who set up our current adsl connection when my husband couldn't (post hardware failure). (Insert manic giggling for no good reason....)