Exactly what software is installed that you cannot replace? Since the system is in Spanish and you don't speak it, how did you use it and install the software? It is in your best bet to find replacement installation media for the software you are afraid to lose and back up any personal data in the program data and documents folders. And then make sure you have all your drivers from the PC manufacturer on hand.
Installing on top of your current install but choosing a folder other than windows will let you be able to keep what you have until you can fix it. If you install over the existing installation without reformatting the hard drive, you will likely have problems. But anything other than a fresh install will cause you headaches somewhere down the road anyways.
It will be best to get everything together then reformat and reinstall.