I thought of posting this based on the no of questions I got from my workshops during past 02 months.

Following are the minimum software requirements for installing SharePoint Server 2010:

• SharePoint Server 2010 is 62-bit only – we will not get a 32-bit version of SharePoint Server like the previous version.
• Windows Server 2008 with SP 2 64-bit or Windows Server 2008 R2 64-bit – SharePoint Server 2010 will not support Windows Server 2003. We need the 2008 version of the Windows Server for installing SharePoint Server 2010. Anyway, R2 of Windows Server 2008 will come only in form of 64-bit and that helps us to make the right choice.
• SQL Server 2005/ 2008/ 2008 R2 64-bit – we can use any of the versions listed above as the database server and it should be the 64-bit. If we are going to use SQL Server 2005, we need to make we apply the SP3 and the CU3 (Cumulative Update) or whichever latest. If its 2008, we need to apply SP1 and the CU2 or whichever latest. If its 2008 R2, we don’t have to apply any other things on top of that.

Minimum Software Requirements for SharePoint Server 2010