Here is how you figure out how much space a directory uses. Pick a folder, any folder, in the left-hand pane by single clicking on it. Now right click and click properties. This should open a panel that tells you not only how much space is used by this folder, but how many files and folders it contains. Pick something big like the Windows directory.
Most people confuse the size of their RAM and the size of their hard disk.
RAM is what the PC uses to operate multiple programs and files simultaneously. Generally, the more RAM, the more things you can do at once. The hard disk is just raw storage space and, as long as there is some space, will not greatly affect performance. But that's not the tip, just info. Today's tip comes from a subscriber that shall remain nameless.