Config help

Hi

I need some help with our postgresql.conf file. I would appreciate if
someone could look at the values and tell me if it looks alright or if I
need to change anything.

The db server has 4 GB of memory and one quad core CPU (2,53 GHz).
The hard drives is on a iSCSI array and is configured as follows:
DB data: 4 x SAS (10.000 rpm) disks in RAID 10
DB WAL: 2 x SAS (10.000 rpm) disks in RAID 1
OS: Linux (Debian Lenny)
DB: PostgreSQL 8.4

The DB is used by a website. It has 75 tables and about a total of 10 mill
rows. The total size of the DB data (data+indexes?) is reported to be about
4 GB when I use the \l+ command in version 8.4.

I have used the following link as a guide:
http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server
This is the changes I have done to the default postgresql.conf file:
shared_buffers = 2048MB
work_mem = 6MB
wal_buffers = 256kB
checkpoint_segments = 20
random_page_cost = 3.0
default_statistics_target = 50

Should I change the default value of temp_buffers or maintenance_work_mem as
well, and what value should I choose? Is there any other values that should
be changed from the default?

And another question: Is there a way to find out the maximum simultaneous
connections that has been used? I think that I could reduce the max number
of connection to save some memory.

Regards

Bjørn Håkon