Customer Discount Mod Required

Hi All
I need to develop a mod that allows me to add a discount field to the customers in the admin section so that a discount can be added to each individual client so that when discount is set to them, say 8 is entered in the field they get an 8% discount on all products and when he is logged in he can see the RRP price and his "You Pay Price" which would be RRP less 8%
so that all clients can be set separate and individual rates of discount... hope this is clear enough

have you tried giving away coupons?

yup..give them redeem coupoun for free