I am a first time buyer of MacBook Pro. I am a software developer and mostly going to use it for programming, movies and listening music. Some times I run heavy duty java applications, so having more ram is ideal for my use case. Considering price and portability, I decided to go for $1499 13" MacBook Pro. If I go for 8Gb RAM, how much memory will be available for OS usage and how much will be used by graphics. Is it worth spending extra $200 for 16 GB?