Hi,
The activation key on your notebook will only work for the version of Windows listed on the COA, so if that's Home Premium, that's the version you need to install. A safe download for Windows 7 Images is on the following link.
http://www.w7forums.com/threads/official-windows-7-sp1-iso-image-downloads.12325/
Your notebooks Product Page can be found on the link below.
Regards,
DP-K