If you have access to a win 7 installation disk, either for one of your other computers or barrow one from a frend.
You can use that, just do NOT enter the activation code during the installation. After install is complete, then activate using the key code on your laptop. Only qualification is that version matchs your version, ie Win 7 Home preium, use a win 7 home premium disk.
As deadlocked stated.
Once installation is complet, drivers loaded, programs loaded and win 7 is activated.
Go to Control panel, Bukup and Image your C drive to either external HDD (prefered) or a set of DVD disk. When image is completed you will be prompted to create a BOOTALE repair Disk so that at any time you can restore windows to EXACTLY as it was when you created the Image.
** Never have the problem again**