Amir,
Based on your statements, it sounds like you either want a "hosted" Small Business Server solution (
http://www.lanlogic.net/dedicated/small-business-server.aspx) that would encompass a variety of shared applications for you and your staff. Or a "Virtual Hosted Desktop" solution (
http://www.virtualhosteddesktop.com/) that would create a more individual solution for each user.
NOTE: The links are an example of each solution (I have no stake in either).
If you want to give more detail on the requirements, I'd be happy to elaborate.
Thanks,
Dan.