Error: out of memory in create table as

I'm having memory problems. I needed to materialize a couple views
(create table t as select * from v) to get acceptable performance from a
small data storage system I'm building, but now I get out of memory
issues on that statement. It is near the bottom of about a 40 line
function, and it completes up to that point, but when I try to run the
create with only about a million rows, it fails:

ERROR: out of memory
DETAIL: Failed on request of size 856.
CONTEXT: SQL statement "create table gwt as select * from gworktick"
PL/pgSQL function "processadd" line 30 at SQL statement

I don't see any temp files being generated on disk. Attached is our
postgresql.conf file. We have little Postgres experience (mostly either
Oracle, Sybase IQ, etc..)

-jason

P.S., lack of an upsert is really killing us.