Is your current windows 7 working OK? Do you have a problem with win 7 that requires reloading it.
A) If Win7 is working fine, then:
Best method is to use windows 7 backup function (located in windows control panel. This will allow you to create a image file that can be placed on DVDs (3 or more), or onto a backup external HDD. Once you have created the backup you will be prompted to make a "Bootable" repair Disk. Using this Back-up is better than re-installing win 7 as it will restore your "C" drive to the same configuration as when you made this back-up. You will NOT have to reload drivers, reload programs, reactivate - about a 15 min task to completely restore windows 7.
B) If your windows 7 currently is corrupted and can NOT do above, then:
1) will need to order a Installation disk from manuf, OR
2) Barrow a copy of Windows 7, perform a CUSTOM installation (DO NOT enter your Lic Key during the Installation). You will then need to go to the laptop Maunf website and download/install the drivers for your laptop. When completed installation, then activate by entering your Key that is on the bottom of the laptop. THEN PERFORM step A