mere pas dell laptop hcore i3 is ki pehle se windows 8.1 installed h ab main windws 7 install krna chahta hu ,,,,kia koi aesa triqa h agr main windows 7 se dobara 8.1 p jaon ,,,, kisi external windows 8.1ki cd k bghair matlab is ki pehle wali orignal 8.1 p jana chahu to aesa ho skta h,,??? matlab is w8.1 ka backup ho skta h kia ?puri 8.1 ka