mysql eating too much cpu

Greetings. I have scoured through usenet to find out how to help my
server.Here are my specs
Dual P4 2.8G
2GB Ram
Redhat Ent. Linux 3 ES
mysql verson 3.23.58

Here is what I have in my /etc/my.cnf (I found these settings in a
usenet forum)

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
set-variable = thread_cache=128
set-variable = thread_concurrency=4
set-variable = myisam_sort_buffer_size=64M
set-variable = key_buffer=784M
set-variable = max_allowed_packet=1M
set-variable = table_cache=512
set-variable = sort_buffer=2M
set-variable = record_buffer=2M

[mysql.server]
user=mysql
basedir=/var/lib

[safe_mysqld]
err-log=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

I often see the cpu usage above 80% when running top. Can someone
suggest what I need to tweak in order to help this poor server out? I
run a clan website for gaming and rarely have more than 100 people on
at a time, most times it is less than 50.

I am not a mysql guru, I am a network guy, so be gentle.

Thank you!