HD files and folders collects dust

Recently I've noticed that my HD has left only a little space. Wondering how can it be I started searching for an appropriate software that will answer my question. Googling here and there I finally found what I was looking for: JAM Software's TreeSize Professional.
This great software is analyzing the HD completely and gives you several easy to understand gauges regard the files and folders resting in the obscurity of the HD (take a look).

What I found:

• Need for Speed Carbon (didn't play it for a long time): 6GB
• Some old help files of an ancient IDE which I removed a long time ago: 1.2GB
• Unused Flight Simulator aircraft files: 2GB
• Images and movies I never knew I'm still keeping them: 3GB
• Very very old documents, PDFs and PPT files: 2GB.
  Sum: 14.2GB (!) of wasted place.

Satisfied, I can now Install Command & Conquer 3 - Tiberium Wars.