WSUS is the only prerequisite to enable software updates in ConfigMgr. At a minimum, you must install the WSUS Software Development Kit (SDK) on the primary site server for the site where you are enabling software updates; this is accomplished by installing the WSUS administrator console. You must also install the WSUS server component on either the site server or another accessible server that meets the requirements for WSUS, as listed at http://technet.microsoft.com/en-us/library/dd939928(WS.10).aspx:
• Windows Server 2008 R2, Windows Server 2008 (with SP 1 or SP 2), or Microsoft Windows Server 2003 with SP 2, Windows Server 2012
• Microsoft .NET Framework 2.0
• Internet Information Services (IIS) 6.0 or later ...