My brother has a Core Duo Macbook with 512 mb RAM, and hes looking to upgrade to Leopard (i have the family pack). Im going to get him some RAM and install it for him then upgrade him to Leopard. I cant decide if i should get the 512mb for $20 or 1gb RAM for $33. Heres they are 1gb and the 512 mb. Is 1gb RAM a big difference then 1.5gb RAM?