It's not easy to answer that without knowing how many people will access and how they will work with sharepoint. It's like asking what engine you need if you buy a new car without knowing your driving style and if you like to pull a trailer.
You need (for SharePoint 2010): - Windows Server 2008 R2 / 2012 - Optional (but usefull) SQL-Server 2008 R8 / 2012 - Optional MS Office Plus (if you want to provide office services) - A connection to AD
For SharePoint 2013 you should run Windows 2012 and SQL-Server 2012
Hardware for good working for up to 150 workers: - 4 Core - 8 better 16 GB RAM
SQL-Server: - 2 Core + - 16 GB RAM
You should perform a farm installation even if you install everything on one machine.