To increase your server performance and stability, it is very recomended to tune your mysql server.
You can find complete info about mysql server tuning here - http://dev.mysql.com/doc/refman/5.0/en/optimizing-the-server.html

Here I give main tuning variables.

You can tune your mysql server by modifying mysql configuration file my.cnf. Usually it's located at /etc/my.cnf.

You can add these lines into [mysqld] section of my.cnf:

[mysqld]

#if you use your mysql server only locally ( usual way ).

skip-networking

#to enable automatical recovering of mysql databases in case of power fault, for example.

myisam-recover

#to increase key buffer for better performance:

key_buffer = 32M

# for mysql 3.23 use set-variable=key_buffer_size = 32M instead.

#to enable query cache for better performance ( only for mysql 4.0 and up ) - very recommended!

query_cache_size= 32M

query_cache_type= 2

#If you don't use innodb and bdb tables in other mysql applications:

skip-bdb

skip-innodb

#Just in case your sites will grow to more than 1,5-2 millions visits per day

#we will increase maximum memory table size to keep info about all surfers :)

max_heap_table_size = 67108864

#for mysql 3.23 use set-variable=max_heap_table_size = 67108864 instead.

After changes to my.cnf done, restart your mysql server.