Quantity box on cart page query

Hi, i have a query, i have a store that has product i reckon people will only buy one of, etc DVDs, books etc

on my product setup i have 'Products Quantity Box Shows:' set to 'No, Do not show Quantity Box '

this gives me a nice BUY NOW button which looks better, but when i reach the cart page i would like the option for a customer to change the quantity at this point

at present i can only acheive this but setting 'Products Quantity Box Shows:' to 'Yes, Show Quantity Box' but the this removes the buy now from my listings, and it requires the user to enter an amount,

is there a way of still enabling the buy now button but allowing a quantity to be changed on the cart page?

Cheers

Rob