There is a windows 10 Upgrade campaign from Microsoft. Automatic Upgrade system had been insisting upgrading to windows 10. I tried but I failed several times. Error message is always same: Intel(R) Dynamic Power Performance Management. Unistall it but it never is unistalled. I tried to upgrade several times with no sucess and it took a long time to try one time... you waste your time.

Somehow I found the problem is 32 bit mode windows and I need to change into 64bit mode. It itself can be done easily but only all data will be erased at the time.

Now I exchanged the internal HDD upgrading to 1TB. It is time to do a clean install and change into 64bit mode and then upgrade to Windows 10. I had been curious how it runs better than Windows 7.

Change into Windows7 64bit mode was easy. Just boot the bios and select a recovery. Choose 64bit mode while recoverying. That is it.

Then Upgrade from the Microsoft Webpage. This time no error happens and it was done!

The screen resolution was wrong the first time, but it was solved automatically.

it gets much faster. But there are three factors here for the results. I don't know which ones are the best contributor, probably all of them:

1. larger HDD(240GB -> 1TB)
2. 64 bit mode(when you clean-install, the one 1TB partition was created.)
3. Windows 10

Conclusion: it gets much faster and I am satisfied with the new system.