HELP.

I am about to launch my new web site, but there is a problem!! I have been using 'microsoftfrontpage' to design the site, but now discover that there is no shopping cart facility with this. I need to find free(preferably)shopping cart software, compatible with frontpage, and with 'worldpay' software.
If the shopping cart can be ofered with the hosting service that would be a bonus. Can anyone assist?