Have you considered using a hosted MS Exchange service? This will give you all of the benefits of using exchange without the headaches. I use Mi8 (http://www.mi8.com) They are very good but maybe a bit on the expenisve side. If server based spam filtering is not important to you, 1&1 offers cheap exchange hosting (http://www.1and1.com). You can find a listing and ratings of exchange hosting providers at http://www.msexchange.org/services/Exchange-Hosting/