Present status: Ubuntu 12.04 installed and working. Want to install windows 7, keeping it a dual boot. I have only installation files of Windows 7. What should I do?
First, use gparted to make space for the Windows 7 partition.
After that, you can simply use an ISO with your Windows product key; Microsoft actually makes the ISOs available for download online via Digital River CDN links.
Or, if you don't want to download the ISO, the installation files option will probably have a means of installing to just the empty space, rather than erasing the whole drive (however, I have never used this installation method myself).
After that, you'll want to boot onto an Ubuntu LiveCD so that you can repair your GRUB installation.
I doubt you can do that by Windows 7 installation files which are let free in a drive. And you have to check with Windows forum for the files you got to get a DVD out of it. But if you got ISO of the windows7, than you can make it a DVD,than by making Partition in UBuntu drive using Gparted, than can install it I believe. Since as far I know, if from Windows installation files, it won't integrative together to form the bootable disk