ColdFusion or PHP:Which would be better?

I apologise if there is a similar post that I may have missed while searching, but here is my issue: As a website developer, I foun myself at a point of confusion. I have a client who has enlisted my aid in designing an eCommerce site. I have been trying to some research and have found that this type of application could be done in either ColdFusion or in PHP. The problem is that I have no real experience with either beyond an email form that I wrote in PHP as a backend for a Flash site. The database that I will be using to store my information is MySQL. I really would like for an experienced programmer to explain the pros and cons of using ColdFusion and PHP and which might be better to implement for this type of site. Thanks.