Computer help needed

[Ozmanks]

I'm going to be buying a computer soon and I have a few questions about what I need/don't need.

Which is better: 2 GB or 3 GB of RAM?

Is there a huge difference between 320 GB and 500 GB for your hard drive?

Should I get the generic speakers or would it be cheaper to go and buy it from somewhere else?

Should I upgrade for a better processer?

Thanks.