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Perhaps I'm wasting my time trying to post a legitimate message in the midst of all this nonsense, but I'll try to answer the question of "how slow does a modern Mac get?"
I have an iBook 600MHz with 384MB of RAM. So it was low-end over a year ago. It's certainly no iMac G4 800MHz (my other, main machine), but it's OK. Running Jaguar, it's fine for surfin' the Web, e-mail, Word docs, programming (Cocoa development's pretty swift on this baby), and some lightweight multimedia stuff. Don't expect to get good game performance out of this.
Of course, this is all somewhat moot as the new "low-end" iBook is already way better than what I got. With a faster processor and system bus plus a decent graphics card, I imagine it's a way better performer than my machine. But my point is: OS X Jaguar running on an older, so-so machine isn't bad at all. A new machine? Snappy.
Of course, as always YMMV.