How did you get v1.7 installed in the first place? Or, the better question is, why did you install v1.7? That version is ANCIENT. Even if you ran the installer for the current version of NI-488.2, it would likely leave what's already there. The issue is that there is no WinNT folder in Windows 7. You could run something like Revo Uninstaller. When it tries to run the uninstaller you'll still get the error, but Revo Uninstaller may be able to clean up the mess left behind.
Next time please check to see that the versions of software you are installing is compatible with the OS version.
