oscommerce is a good script but it is hard for non-technical people to set up. webmastercart seems to be an easier option, so do zendcart and x-cart.

if you are really non-technical, I would suggest hiring someone with experience setting these up as sometimes even the simplest things (like setting up shipping depending on where the order is coming from) are really hard to do.

good luck!

cheers,
Luke