Memory nearing limit

I'm having this problem with bootcamp. I have it set to about 100 gb and am using a macbook pro 13 with 500gb.

I had tried installing some game from the internet with no success and some error messages. It wasn't until after this, I noticed that most of the hard drive space was taken up. Out of the 80 gb that was free, I was suddently down to 10. I've checked to see what programs I have installed and with them all added up, it doesn't nearly come to use that amount of space. I believe it to be a virus or some self replicating file that's taking up all the memory. Has anyone else had this problem?

 

It was actually sonic generations from pirate bay. That's where I went wrong. I'm running the winDirStat now.

Running off 4 gb ram If I remember clearly.

 

Correction. There's about 75 gb partitioned for windows. It seems my program files are about 30 gb. Steam is taking up about 18 gb. I needed steam for school surprisingly. I will see what I can do about cleaning up.