do you have a computer geek - one of the biggest soaks on the computer is Microsoft itself if you are on Windows....they do not delete their updates....on my last pc, half of the memory was taken up by them.
I was using 44 out of 80 GB on my last Asus - moved to a new one (same price) and got 280 GB and the part used had dropped to 24 GB, that being how much Microsoft had taken with their updates. It doesn't cost that much if you have a local pc repair shop - and worth getting it cleaned if it has some age.