This is a bit on the geeky side, but I guess this thread is anyway.

I use Linux and Evolution to manage my email, calendar and contacts. I store them all on the Exchange server. I think tell my Windows Mobile device to sync directly to the exchange server. I don't sync mail, just calendar and contacts.

Overally I would say that the experiance is far less satisfying than using thunderbird for mail, however the integrated calendar and contacts is nice. Its better than using outlook - I just couldn't get used to a few "features" of outlook.

I know a few people @ work who use thunderbird, but filter all their meetings to a different folder and use Outlook Web Access for those. You could still sync direct to the exchange server in that model, but your contacts wouldn't be preserved.