Honestly, don’t waste you time with the free WP e-Commerce plugin. I documented my pains in a previous post.
For $25, go buy this, WP E-store.
I had an install problem that ended up being from another plugin I had installed. I got an email back from support and they helped me trouble shoot it and set it up fine.
Works great, price is right, good documentation. I gladly give my $25 for a working product.