I've been looking at shopping cart solutions on behalf of a client, and Zen Cart seems to get a pretty good press and be well supported, which leads me to want to adopt it. However, I currently have no PHP knowledge, and I'm wondering how much of an issue that is for working with it.

I'm primarily a Java developer, very familiar with web technologies, so I'm not a newbie to web applications at all, I've just never used PHP. I am also looking at KonaKart, a Java shopping cart, but Zen Cart looks to be more fully featured, and hosting seems to be MUCH easier with a PHP/MySQL app.

Do I need to throw myself in at the deep end with PHP, or is there no need, at least initially, to get my hands dirty (to mix metaphors)?