Dynamics NAV Integration Options

I have been tasked with creating an integration proposal for a client that uses Dynamics NAV.

We don't have any COM development skills, and like to create loosely coupled designs using HTTP / SOAP / XML (ideally), or alternatively XML over FTP / File System etc.

I have been searching on google on NAV, and I can't find a simple summary on the options, a sentence on each.

Could anyone please give me a quick overview of the options, and what is required from the client to configure NAV to get each option working.

Thanks

8)