I would second (or third..or fourth) the suggestion to try nginx. It's much lighter than Apache. You can use it as a proxy, but I would probably just use it as a primary httpd. Wordpress isn't too difficult to setup with nginx, either.

Thanks for the advice, trying Nginx on it's own with php5-cgi & it's consuming more memory than Ngnix as a proxy to Apache, see screen shot.
any other tuning advise?

It's using almost identical memory. Both apache and php-cgi are using 13MB per process in addition to the 29-31MB in the shared cache.

If you want to go without apache as a backend, you really should go with php-fpm instead of php-cgi.

php-fpm is another server interface like cgi that builds on cgi and adds a number of important features and improvements for process management. It was made part of the official php package in 5.3.3 and is part of the Ubuntu Maverick version. php-fpm has nice logs and stats and is pretty much tailored to use behind nginx.

From your php version of 5.3.2-1ubuntu4.5 you're on Ubuntu Lucid, you can use my repo for php-fpm.

add-apt-repository ppa:brianmercer/php
aptitude update
aptitude install php5-fpm

Or you could upgrade to Maverick.

You asked about mysql tuning. Get mysqltuner.pl and tuning-primer.sh and start getting familiar with mysql directives.

Tried using this method. Everything installed OK. Now how do I enable php-fpm? my php info is still saying:

Server API : CGI/FastCGI

and when I look in my processes it says php-cgi.

You can start(/stop/restart) php-fpm with

sudo service php5-fpm start

That is the recommended way to start/stop daemons and is compatible with upstart and old scripts.

Killing php-cgi depends on how you started it. Maybe "sudo /etc/init.d/spawn-fcgi stop" or if necessary "sudo killall php-cgi" or "sudo killall -9 php-cgi"

You can also save RAM by using less PHP processes, if you've got lots of spares. I've run very memory-constrained boxes with as few as two, since that's sufficient for light (to possibly medium) load if you don't have any long-running scripts. I wouldn't suggest that for an actual box if you've got RAM to spare, but 4 to 6 goes a long way if there aren't any long-running scripts.