SQL Server/Access ADP connection failure

Hi All, I have successfully installed SQL Server 2008 Express on my stand-alone Windows 7 pc.  I've logged on to it, created databases, tables, etc. and have successfully linked to an Access 2007 database by specifying the machine source as SQL Server (ODBC). I am planning to employ ADP instead of linking the tables to Access.  Per instructions I created an ADP database and when given the choice 'Do you want to connect to an existing SQL Server database?' I choose 'Yes'. On the Data Link Properties screen, server name field (my SQL Server name doesn't appear in the drop down) I key 'HP\SQLExpress'. After selecting 'NT' security I try to select the database on the server whereupon I get: 'Specified server not found'. When I log on to SQL Server management studio I use 'HP\SQLExpress'. So why doesn't it find it on the Data Link Properties screen? Thanks!Mr Spadafman