SQL> ed
Wrote file afiedt.buf

  1  select * from (
  2   select job,sum(sal) s from emp group by job) a
  3  where rownum <= 4
  4* order by s
SQL> /

JOB                S
--------- ----------
CLERK        3462.23
PRESIDENT       5000
ANALYST         6000
MANAGER         8275

SQL> 

I am sorry , i gave you a wrong information.
Actually, this is not a correct method (Eventhough
it MAY give the expected result MOSTly)to derive 
the TOP N rows.
Becuse we are ordering the rows, out of subquery.
so this should work fine in 7.x also. 
( must be > 7.1.6)
I have no instance with 7.x. So i didnt test it.
SQL> ed
Wrote file afiedt.buf

  1  select job,s from
  2   (select job,sum(sal) s from emp group by job)
  3   where rownum <= 4
  4*  order by s
SQL> /

JOB                S
--------- ----------
CLERK           4150
PRESIDENT       5000
ANALYST         6000
MANAGER         8275

SQL> ed
Wrote file afiedt.buf

  1  select * from
  2  (
  3  select job,sum(sal) s from emp group by job order by s) a
  4*   where rownum <= 4
SQL> /

JOB                S
--------- ----------
CLERK           4150
PRESIDENT       5000
SALESMAN        5600
ANALYST         6000