10.5 Server mail and iCal server vs Kerio

I've been wanting to migrate away from an offsite exchange server, so my choices are Mail/iCal server (10.5) or Kerio.

Needless to say, it'll be much cheaper for me to use my existing 10.5 servers to handle mail rather than purchase Kerio plus cals.

So...
Anyone have any feedback using the built in Mail and iCal server? I have about 40 mail users, 60% Mac, the rest Windows. Using Entourage 2008 (Mail is also ok) and Outlook 2007 on the PCs.

Any feedback is much appreciated

Well, to save you some reading, No, I have no actual experience with either product. But here's my take on things anyway.

I'm not aware of any real way to synchronize Outlook with an iCal server. You can send events back and forth (even regular desktop iCal and Mail can do that) but I don't think you could sync without a third-party add-on, and that may or may not be reliable. It might be better if you could switch the Windows users to Sunbird or something.

I've heard the Kerio product gets expensive, since it's subscription-based, but it might be cheaper than a hosted Exchange service.

Sun has a Communications Suite that supports iCal and Outlook (through an add-on) and it's a free download, but it won't run on an OS X server. (Linux, Solaris, or Windows, only.) They do charge for support.

Yahoo's Zimbra product supports iCal (caldav) for free, but Outlook costs money.

Have you looked into Google Apps for business? Google will happily sell you a hosted and supported version of Google Calendar and GMail that will work with Outlook, iCal, or through the web. Their SLA is pretty weak (three nines...that's almost four days of downtime per year.)

technologist, thanks for the reply. My windows users are, for lack of a better term, stubborn. I can save myself the headaches and keep them on Office.

iCal server is going to be a problem, as I suspected. I'm guessing that Kerio is going to be my best bet, unless I can convince my cfo to replace the remaining PCs with Macs within the next fiscal quarter. Highly unlikely.

Thanks