Currently doing some reading on Islamic theology. I'll try and get an answer for this. My initial reading into this subject gave that link (which was posted in another thread and posted here but Mod's deleted it cus it was how we say not right --- I did not know this at the time. Sorry!)

So, like I said. I'll do some reading on this subject tonight - I recently went to an islam awareness thingy at uni and picked up some really good resources which will form up some of my background knowledge on this subject. Hopefully it will explain the economical side of Islam.

Probably get an answer to you tomorrow at the very latest.