Before going abroad,
I wanted to clean up my old pc,
I re-install Windows7.

Install DVD was Windows7(not SP1),
So I had to reboot over and over again.

There were so many patchs (over 180!) I had to apply!
It took five hours to finish install.

On the countrary,Puppy Linux install took less than 10 minutes!
I will use Puppy Linux as main OS.