Hi Moran
There are a number of Live Chat suppliers, you also need to consider what extra features you may or may not require.
Do you need multiple people able to answer the Chat?
Do you want to personalise it? I was on one the other day and it said "CS Rep" as opposed to Bob
Some allow you to send emails at the end or print the chat, others let files be uploaded, some allow remote control, i.e. letting you guide the client around your site.
This one from CuteSoft is very powerful, speak to Aderson he may know them from our WSI days
The hosting company I use uses http://www.liveperson.com/ which from a "recipients" end seems really good
Do you want one that takes an email if the call is not answered?
Tells you how many people are in the queue ahead of you?
Bottom line, define your needs then take up free trials :-)
http://store.dotnetnuke.com/home/product-details/free-live-chat-software-for-dotnetnuke
Hope this helps
Dave