Ram usage gets high fast
 

For some reason, after opening and closing some programs(ten or more), phisical RAM usage gets to 400mg, and doesn't drop(even tough I've already closed the programs).
Is this normal(cache)?

It's normal, Linux uses your ram incase another program needs to use it... or something like that.... :)

What's the point of having all that RAM if not all of it will be used.... :)

This is asked twice weekly at least, a quick search would display that this is totally normal.