High cpu load from database.

hi.
We are getting high cpu load spikes on a dedicated server Quad Core Q6600 with 4gb ram
The site is a rss agregation site with around 150 feeds.

The server every two days crashes with mysql usage to 100%

Our database is mysql with MyISAM utf8_general_ci
The mysql configuration

max_allowed_packet = 64M
max_connections = 200
max_user_connections = 150
key_buffer = 256M
table_cache = 2000
thread_cache_size = 286
interactive_timeout = 25
wait_timeout = 1800
connect_timeout = 10
max_connect_errors = 1000
query_cache_limit = 32M
query_cache_size = 128M
query_cache_type = 1
tmp_table_size = 32M
max_heap_table_size = 32M
long_query_time        = 5

I would like to ask how could we debug the situation.

I would like to ask what are your suggestions about a better database setup.
Should we change to InnoDB ?

Manos
http://websynergy.gr/