I wouldn't recommend downloading Windows 10. I tried it on two of our machines and had problems with both. One rolled back to Windows 7 ok. The other took me 10 days to reinstall and get going again - wouldn't boot, wouldn't do Windows 7 updates - nightmare.

If you do want to try it make sure you have all documents, music, photos and videos backed up/copied onto an external drive or usb sticks. Write down a list of all installed programs and all their product codes. In case you need to reinstall from scratch. Make sure you have a full system image as well and recovery discs for reinstalling a system image. If the laptop is older than 2 or 3 years old it may not work fully on Windows 10 (yet). If it uses Intel GMA 3600 display graphics it won't work!