Forgive me if this has already been asked and answered, but I have been reading for a couple of hours and am still a little confused.

What is the differecne between EP 1.2.5.4 and EP 4.0? Do they work with each other or are is 4.0 an updated/rewritten 1.2.5.4 or what?

I am setting up a Zencart site for my sister in law and she is not web savvy and need a relatively simple way to add and remove products.

Thanks

Tom