server is busy messages
 

I have a vBulletin 3.8.4 Patch Level 1. It has been experiencing a lot of problems recently. My users are getting a lot of "The server is busy" messages often for an hour at a time. Also the board can be very sluggish for long periods of time.

PHP 4.4.7
MySQL Version 4.1.22-standard
MySQL Packet Size 32.00 MB

Data Usage 4.34 GB
Index Usage 2.00 GB
Unique Members Today 784
New Posts Today 2*178

Server Load Averages 2.66 2.15 1.87 | 279 Users Online

Am I over stressing my server? Do I need to upgrade php or mySQL?
Am I missing some kind of maintenance that will speed up the board?

Any help would be appreciated.
thanks*
-dan