Upgrade SharePoint Portal Server 2003 to SharePoint 2010
There is no direct path to upgrade/migrate from SPS 2003 to SPS 2010. Unfortunately you must go via the WSSv3/MOSS 2007 stage!
https://blogs.technet.com/steve_chen/archive/2010/03/31/upgrade-sharepoint-portal-server-2003-to-sharepoint-2010.aspx