Hardware and performance

We currently have a Dual Xeon 2.8 Gig 12 Gig of RAM, SCSI 10K HD 300 gig RAID 5 disks. Dual 100M NICs one for internal and one for external. We do have our DB and Web servers split both running on Linux Cent OS 5-2 servers one for each. We are seeing our DB taking a huge hit in preformance during the day at our College. We have about 370 of classes currently and about 200 concurrent users at one time with about 10K users using LDAP with AD to handle the accounts.
PHP 5.1.6
MySQL 5.0.45
Apache 2.1

Error:Database connection failed

Below is my.cnf file any help on what we need to change to help improve the preformance would be great appreciated

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
max_connections = 200
max_user_connections = 200
myisam_sort_buffer_size = 380M
join_buffer_size = 12M
read_buffer_size = 12M
thread_cache_size 286
interactive_timeout = 25
wait_timeout = 1800
max_allowed_packets = 2M
max_connect_errors = 1000
query_cache_limit = 1M


#The size of the buffer used for index blocks. Increase this to get better index handling (for all reads and multiple writes) to as much as you can afford; 64M on a 256M machine that mainly runs MySQL is quite common.
key_buffer_size=256M
#Each thread that needs to do a sort allocates a buffer of this size.
sort_buffer_size=12M
#
#
#Each thread that does a sequential scan allocates a buffer of this size for each table it scans. If you do many sequential scans, you may want to increase this value.
read_buffer_size=10M
#The number of open tables for all threads.
table_cache = 1024
tmp_table_size=12M
#
#
#The memory allocated to store results from old queries.
query_cache_size=512M
#
#
#Max packetlength to send/receive from to server.
max_allowed_packet=1536M
#


[mysql.server]
user=mysql
basedir=/var/lib
#
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid