Personally wouldn't use any chat which was based on php/ mysql, especially one which is no longer supported.

My trial of three of the best I could find concluded last Friday. The winner by a fair margin was zopim (using the free version). I took out a 12 month subscription to get all the extra features including monthly reports. I think the analysis alone is worth the subs.

Note: One of their best selling points is that the 2 week trial is a full version without having to fork over your credit card details. Some of the competition could learn from this business model. Plus it has an iphone app, quite useful if you're away from computer.