Download legit one from here and use legit code you have to activate
http://www.w7forums.com/threads/official-windows-7-sp1-iso-image-downloads.12325/
Downloading is not an option as I have a crap connection and it would take days .if there is not a file already on my pc I will have to look into making on.
Your only option is to either download or use your original disc. Incidentally, how fast is your internet connection?
I don't know the speed as I haven't used it much since I moved.
But I know my son moans about it with his xbox and my misses complains about dropped connection when she is using her ipad.
I'll use a program to create one should be OK.