If you do decide to use the Oracle 7 functions, your code should look like:
putenv("ORACLE_SID=[Your SID]");
putenv("ORACLE_HOME=[Directory path for Oracle]");
$user = "user/pass@tableslace";
$conn = ora_logon($user,"");
$curs = ora_open($conn);
ora_commitoff($conn);
that's what i have done in the past.