It's definitely unnecessary... this last upgrade, if I recall, fixed the daylight savings time (that the US just changed). Regardless, you are probably never using java... and I'm sure the version you have will be fine. That being said, I generally recommend staying up to date on all of Apple's automatic updates... It won't slow anything down or take up much more space (replaced on your harddrive, so likely undetectable differences in storage... this won't affect your RAM (fast, temporary memory) at all.) But Java truly won't make any difference to you. Don't update if it's a big pain.