Remote workers

I would like to develop the optimal method for our users to work. I have 2 users who are on the road 75% of the time. Providing them with the means of accessing data on the server and emails is my goal. I am running SBS2003 and have provided remote WEB mail but want to optimize the environment. Should I use the Public Folders to store data? I’ll assume I can access the folders through Outlook Webmail? They have also asked about a Blackberry or Treo device for instant access.
I would like to hear how others have configured there network for mobile users