Where can I find drivers for Windows 7 on an iMac without Boot Camp Assistant?
They are on one of the installation disks that comes with your iMac. Also, I'm pretty sure the drivers get installed if you download and run a "Bootcamp Software Update for Windows"  from Apple's support site. They are usually 200MB or up downloads that come packed with drivers for windows, so give it a try in case you can't find your cds.