I'd guess that there's no ODBC DSN called "TestCasesXP2K" set up on your PC, or if one exists it isn't a System DSN and isn't available to the current user.

Try this instead:

DBI->connect( "dbi:ODBC:driver=Microsoft Access Driver (*.mdb);dbq=C:\
+\path\\filename.mdb", "", "" );
[download]

replacing "path" with the path and "filename" with the name of an Access database file. The two empty parameters at the end are username and password - if the database requires such fill them in also.