Of course, last week I bitched about what a piece of crap Microsoft Entourage is. Today I actually found something which might make it possible for me to get the full Exchange calendar functionality, including checking invitee availability, while still using Mac Mail and Ical. It is this absurdly-klugey-to-set-up app called DavMail, but after a couple hours tinkering with it, I think it actually works. At least part of the time anyway.
Now I just need to re-do all my rules in Mail, which actually kind of sucks since it doesn't look like its logic is any better than Entourage's. But at least it has real threading. Sort of. I just get far, far too much mail at work to deal with a half-assed mail client. Let alone a one-sixteenth-assed mail client like Entourage.