In addition to using explorer view, as [it was already answered][1].   

This is basically the question on how to copy a form library with its content which is easily searchable.  

In the same site collection, in Form Library Settings I would have used "Save Form Library as template" having checked "Include Content". This template choice will appear for creation of new form libraries.   

For copying a form library to another site collection, it is also possible [to save the created template as STP file][2].   

You can find a few more methods like [granular backup-restore][3], engagement of [Sharepoint 2010 Management Shell (Export-SPWeb / Import-Spweb)][4]m etc.  


  [1]: http://sharepoint.stackexchange.com/a/44631/8319
  [2]: http://office.microsoft.com/en-us/sharepoint-server-help/copy-or-move-a-library-by-using-a-library-template-HA101814157.aspx#_Toc264367900
  [3]: http://blogs.msdn.com/b/russmax/archive/2009/10/21/sharepoint-2010-granular-backup-restore-part-1.aspx
  [4]: http://technet.microsoft.com/en-us/library/ee428301.aspx