Advice please!!! Ordered a bran new MBP base model 13in. Already decided to upgrade HDD to 500gb butthinking about ram. Is it worth going from the base 4gb to 6gb??? Budget/wife won't alllow me to go to8gb. Ultimately will be using this as a desktop replacement, will be photo editing (not cs but pse). Streaming alot and general desktop type use what do people think? Stick with 4gb upgrade to 6gb or fight for 8gb???