Clean up your computer once in a while!

A couple of weeks ago, I observed that my computer got so damn slow I started wondering what happened. When I checked the free space it said I have just 2GB of free space. A month ago it used to be 20 GB. Something terrible happened which I was not aware of. I didnt know where to start looking. So I started checking where the most of the junk lied. I saw there were a lot of files which I no longer use. I deleted them. I deleted few other files, some debug files, it was still just 2GB gain. I looked under Start->Programs -> Accessories -> System tools -> disk clean up. It is a beautiful tool that Windows introduces (I dont know when) to clean up the disk. I ran the disk clean up utility. It took its own sweet time to return back with its analysis. A whooping 16.7GB that it says can be cleaned. It was mostly temporary files, some dump files etc. But I could have never laid hands on them manually. They were hidden in some n number of folders below C:\
After I did the above, my computer was considerably faster. I also ran a spyware software just to make sure I didnt accumulate any of the spyware/adware programs while browsing the internet.
Overall, I am much better now and my laptop is much faster.

While doing so I found out something very interesting. The same happens even at our homes. We keep accumulating a lot of junk (old clothes which you never use, some old mails, magazines, books) that occupy a lot of space and apparently serve no purpose except to take the space and invoke negative feelings in us. Once in a while, we should get rid of them to make more space and peace of mind.
Any suggestions folks?