Earlier I had two partitions, D(logical) and C(system). Now, I have added a new HDD and I've made two new partitions, B(logical) and S(system), now I want to format C and install Windows in S partition. What's the best way to do it?
If you set your bios to boot from disk and not HDD then during the install process you will get a chance to choose where you want the installation to take place.
This web page from Microsoft has an FAQ on installation. Look under 'should I use the Upgrade or custom option during installation'. This should give you all the info and 'how to's' that you need..
Thanks kemical, also, when I format my old system partition via the installation do I have to install Windows on that partition? And how do I choose which system will boot after installation? Or should I format via EASEUS Partition Mater after the installation?
As above you will reach a screen during installation which will allow you to format or add and remove partitions. Obviously formatting will mean you will lose your old installation. So don't worry about 'choosing which system to boot from' as you put it as the old windows installation will be gone.