Personal Oracle 8.1.5 ODBC Win98

I have an Oracle 8.15 default database (sid = orcl) on a Win98 PC. I am trying to connect from Access 2000 via ODBC. I have started my listener and I think my tnsnames.ora file is OK but I fail to connect. Running ODBC test gives the following error

SQLSTATE: NA000
Native Error Code 0
Driver Message [Microsoft][ODBC Driver for Oracle][Oracle]

My Oracle SID is ORCL and my tnsnames and listener are included below. If anybody could help with what should be a basic set up please let me know

Regards

Sal

TNSNAMES
# C:\ORACLE\ORA81\NETWORK\ADMIN\TNSNAMES.ORA Configuration File:c:\Oracle\Ora81\network\admin\tnsnames.ora # Generated by Oracle Net8 Assistant

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
    (CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)

    )
  )

ORACLE =
  (DESCRIPTION =
    (ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = ORCL))
    )
    (CONNECT_DATA =
(SID = ORCL)

    )
  )
ORCL =
  (DESCRIPTION =
    (ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = ORCL))
    )
    (CONNECT_DATA =
(SID = ORCL)

    )
  )

LISTENER
# C:\ORACLE\ORA81\NETWORK\ADMIN\LISTENER.ORA Configuration File:c:\Oracle\Ora81\network\admin\listener.ora # Generated by Oracle Net8 Assistant

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
(ADDRESS_LIST =

        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
      )


      (ADDRESS_LIST =


        (ADDRESS = (PROTOCOL = TCP)(HOST = oemcomputer)(PORT = 1521))
      )

        (PRESENTATION = GIOP)
        (SESSION = RAW)
      )


      (ADDRESS = (PROTOCOL = TCP)(HOST = oemcomputer)(PORT = 2481))

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = c:\Oracle\Ora81)
(PROGRAM = extproc)

    )
    (SID_DESC =
(SID_NAME = ORCL)
(ORACLE_HOME = c:\Oracle\Ora81)

    )
  ) Received on Fri Nov 24 2000 - 12:10:40 CET