So you have Task Manager and System Explorer which basically does the same thing?

If you are lacking space then you only have two options which are either more Ram or another system with

greater capacity.

So cost effectiveness would make the Ram more suitable unless the system is more then 7 years old as then

an upgrade may be a more effective option due to superior speeds and greater capacity.

Have you cleared out unnecessary files,emptied the Recycle bin,cleared Cookies and Cache,removed unwanted

program's,defraged,put icons into folders,etc.