convert an Insert Into... select from... to use COPY ?

Hi All;

I have an sql stmt that runs:

insert into x
( a.col1, a.col2, a.col3,b.col1,b.col2)
select blah,blah,blah
...
from giant_table a,
even_bigger_table b
where.....

I wonder, could I convert this to use COPY into the table (x) instead of the
select stmt?

Thanks in advance