Autovacuum Issue

Hi,

My application is performing 1600 inserts per second and 7 updates per
second. The updates occurred only in a small table which has only 6 integer
columns. The inserts occurred in all other daily tables. My application
creates around 75 tables per day. No updates/deletes occurred in those 75
daily tables (only inserts and drop tables if older than 40 days). Since
only inserts in the daily tables, I disabled autovacuum in the conf file
and I can see it is off stat using show command.

*sasdb=# show "autovacuum";
autovacuum
------------
off
(1 row)*

But the autovacuum is running frequently and it impact the performance of
my system(high CPU). You can see the autovacuum in the pg_stat_activity.
*
sasdb=# select current_query from pg_stat_activity where current_query like
'autovacuum%';
** current_query
**

------------------------------**------------------------------**
---------------------------
autovacuum: VACUUM public.xxxxx**_17_Oct_11 (to prevent wraparound)
autovacuum: VACUUM public.**xxxxx**_17_Oct_11 (to prevent wraparound)
autovacuum: VACUUM public.**xxxxx**_17_Oct_11 (to prevent wraparound)
(3 rows)

*Why the autovacuum is running even though, I disabled ? Am I miss anything
?

And also please share your views on my decision about disable autovacuum
for my application. I am planning to run vacuum command daily on that small
table which has frequent updates.

Thanks,
Ramesh