Exchange Options

In my spare time I manage my wifes small business network (7-10 users). Shortly after I got them all setup with ISP hosted POP3 mail they started requesting shared calendars, shared contacts and shared folders. They do have SBS Server 2003 but I never setup exchange because I was planning that they keep their hosted email.
Can anyone recommend what I can do to accomdate their needs and keep my administration to a minimum still. Keep in mind that I can only spend about 2 hours a month administrating the office at this point.

David
Sacramento, CA