I'd do somethings like:
select * from (
select id, sum(col1), sum(col2) from tablename group by yada
) as a [full, left, right, outer] join (
select id, sum(col3), sum(col4) from tablename group by bada
) as b
on (a.id=b.id);
and choose the join type as appropriate.
Thanks! Your idea worked like a champ!
Mark