perfomance question

Hi all,

I have a large site currently hosted at following machine:

Linux 2
64MB RAM, 2x100 MB Swap

Apache 1.3.X ( 120 connections, 2 min )
PHP 3.0.18 installed as CGI binary
MySQL ( 150 connections)

sitename: http://picof.com/nmmm

The site have too many visitors and all the pages are connected to the
database, most of them using select joining two tables (users + countries).
Rare new users are subscribed (insert into users) and existing users update
their profiles (update users).

Sometimes the system is overloading (130 httpd's, 130 apache's, 130
MySQL's), swaps about 100 MB and stops serving http requests.

Is there a possibility to improve performance of the computer?
!!!I cannot upgrade the computer!!!

What will happen if I migrate to pgsql? Will I get less memory if I compile
the php as module + zend + persistent connections to the database?

Migration to mSQL version 1 ??? the queries are really very fair...? I dont
think so...

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ok anyway the only question related to group is what will happen if I
migrate to pgsql (and make a lots of indexes)?
--
(if you have suggestions not related to group, send them to me only)

Thanks,
Nikolay