Temporary tables

Hi,

I have to play a lot with temp tables.
Could you pls, give me a hint on emulating them under Postgres.

I have to use them quite often and with 10000 rows each.
I  don't use indices cause I only cache a search result and don't need
any sorting, searching on temptables.

What's faster:

1)
once:
 create tmptable;

many times:
 delete from tmptable;
 insert into tmptable select ... ;

or

2)
many times:
drop tmptable;
select ... into tmptable;

I  prefer  the  second way since I have a lot of concurrent access and
create unique named tables under each transaction.
Unfortunately the DROP thing dumps a core under PLPGSQL function. :(

TIA,
Pawel