It is possible yes. You will need to get a OEM version of Windows 7 in what ever flavor your key is for so Home Premium or what ever your laptop used. You can get a copy from your laptop manufacture but there will be a small charge for it other than that I can't tell you how to get it.
The version you are using now is BIOS activated so when you do the reinstall you will need the key from the bottom of the laptop. It may tell you that you need to do a phone activation but it is easy and will not take to much time so do not worry about that.