I have a new genine windows for my Acer Aspire Laptop

My new Acer Aspire laptop has expires its trial version of Windows and I need a genuine windows now. A friend of mine named Jongjong, an officemate of my brother who have a genuine software of windows lend me his CD. I am so happy because I don't have to buy one because it cost 2000 pesos for one. I am going to erase my installed Windows here and change it to the genuine version. I will also keep a copy of this one so that whenever I have problem regarding windows programme, I can immediately solve it.