Where to buy
Talk directly to the companies that sell Microsoft's hosted services
Microsoft does not sell its hosted services directly to the public. However, you can buy Microsoft hosted Exchange and Windows SharePoint Services from the companies listed here. They should also be able to answer your questions and advise on a package to suit your company's needs.
BT
BT Business offers a number of different packages depending on your needs. The minimum order is 5 email accounts, with optional mobile access and increased storage space.
Cobweb
Cobweb offer a tiered service from basic mail with web access through to full Outlook 2003 client with shared calendars etc
Webfusion
With Webfusion, companies as small as five users can utilise a highly functional messaging system that's easy-to-use, without the heavy investment and effort. Minimum order 5 accounts and price includes Outlook 2003 client.