My question was what operating system I will install to my 9 years old PC. I was undecided between Ubuntu and OpenSUSE. So I researched more deep, and I found out a site who helped me a lot.
I had two choices: OpenSUSE or Fedora. To my surprise, Ubuntu had 90% of recommendation. So I ignored Ubuntu and I tried OpenSUSE and Fedora with LiveCD. After I experimented both, I decided to install OpenSUSE.