This tip can be done in either Windows or Linux. In Windows using the MySQL Administrator go into the Health Tab and then the Performance Tab. Look at the key_reads and key_read_requests numbers. The ratio of key_reads to key_read_requests should be above 1:100 if you can spare the memory. It should be no lower than 1:10.
How do you increase the ratio for better performance? Increase the key_buffer_size value to an acceptable level.