I could not get Kies to work on my 64 bit Windows 7. I guess the drivers only work on 32 bit.
Running Windows 7 x64 here with Samsung's latest drivers...but I've also permanently disabled driver signature enforcement as well...
Try disabling signature check using easybcd free tool, that you can get from http://neosmart.net/dl.php?id=1
Run easybcd, click advanced options button.