Windows SBS 2011 Trial
If you are a small organization with limited IT resources and budget, then it is worth giving Windows Small Business Server 2011 a try! SBS 2011 is designed and priced for small businesses with up to 75 users. It's an all-in-one solution which has been updated to the most current Windows 2008 R2 server technology. It includes a new and improved Remote Web Access, the new Exchange Server 2010 with SP1, the new SharePoint Foundation Services 2010, WSUS 3.0 and other features that allow you to perform automated backups, internal web sites, sharing and controlling resources.
On top of all of that, you get some good protection with features that monitor client computers for antivirus status, update compliance and overall security health. It can also provide you with network-wide protection with integrated state of the art protection technologies.
Download the trial software from here - http://www.microsoft.com/en-us/server-cloud/Windows-Small-Business-Server/trial.aspx