I can’t stand running Windows. I don’t have anything against you if you do, but I’m someone who spends a ton of time in a terminal, and cmd.exe is an atrocity. On the other hand, every company I’ve worked for has used Exchange for mail. This is a problem, since Exchange support is hard to manage on non-Windows machines.
Over the past few years, I’ve tried a lot of things. Entourage is crashy, slow, and takes over the keyboard shortcuts every other program on the Mac uses. Exchange over IMAP tends to randomly delete messages I move between folders. Outlook in a VM is great if I don’t mind going without the extra half gig of RAM and the Windows license. Outlook through WINE kept dropping connections, forcing me to restart it every hour.
Snow Leopard’s integration is great, and something I’ve been waiting for for years, but it doesn’t solve the problems on my Leopard and Linux machines. Finally, I found DavMail. It’s a proxy between OWA and mail and calendar standards, where OWA goes in one end and IMAP, SMTP, CalDAV, and LDAP come out the other end. Once it’s set up on a Leopard machine, it acts almost exactly like the Snow Leopard Exchange support, and it works great on Linux through Thunderbird. I haven’t been able to get the LDAP support working on Leopard yet (Directory Services says it can’t contact the server), but it works great through Thunderbird. I have no idea how I never heard about it before, but it’s something I’ve been looking for for years.
Leave it to Apple to solve the Exchange thing right before I do, but DavMail is going to be one of the first things I install on any non-Snow Leopard machine.