"The Quran forbids usury, not interest. Quite a few 
states in the USA have laws against usury. Usury is 
defined as excessive interest. A Dictionary defines 
usury as 'an excessive or inordinate premium for the 
use of money borrowed',  'extortionate interest', or 'the 
practice of taking exorbitant or excessive interest.' The 
Arabic language also makes distinction between 
interest (Fa'eda) and usury (Reba). The Quran forbids 
Reba or usury."   
http://www.submission.org/islam/interest-usury.html