Chat program for PHP site

I need a chat facility for my PHP website. The chat must be very light on my MySQL database (not using my database would be great)...Must have a section where I can easily change the width and height, background colour and font colour, as well as font size and how often it updates the page information...The chat's members details are derived from a table called members with their first name coming from there... Can't think of anything but if you can ...include it in your bid... Bidders who do not quote what I have asked for will be ignored... Best of luck