Like you, i am NOT a programmer but a store owner. So i hope my view point helps you, i have used both PrestaShop and Magento.
Magento i didn't like, boat ware!
Prestashop is good, pretty templates but the good modules are not free and to get an online shop with the features you need can end up costing 1000s
I also use Zen Cart, while it has the worlds ugliest standard template, if your CSS knowledge is average you can make it look pretty much like anything you want. It has more features built in than the Magento £11k pa has and all modules on the site are free and also a better community too as the forums are open source focused.
Hope it helps.
