How to Increase MYSQL performance

Hello All,

I’m currently running mysql 5 on a server with 6GB of RAM and dual Xeon processors and I wish to take full advantage of the box’s horse power.
Right now mysql runs fairly slow and it only occupies about 1GB of the total 6GB memory. I wish to increase its utilization so that some queries run faster (in memory).
Can someone suggest what changes I can make to have mysql utilize more server resources?

(a lot of the queries are Join queries)

I currently have the following lines in my.cfg file:
[mysqld]
key_buffer_size=256M
query_cache_limit=32M
query_cache_size=256M
thread_cache_size=256M
join_buffer=64M
max_allowed_packet=16M
table_cache=2048
sort_buffer_size=16M
read_buffer_size=4M
myisam_sort_buffer_size =64M

[isamchk]
key_buffer=128M
sort_buffer=128M
read_buffer=32M
write_buffer=32M

[myisamchk]
key_buffer=128M
sort_buffer=128M
read_buffer=32M
write_buffer=32M

Anything I can tweak better?
Thanks
TheHawk

What storage engine do you mostly use? MyISAM or InnoDB?

I’m not sure as I’m a newbie. How can I check?
Thanks