Hi bertjan,
There is no need for rootkit scanning in the form that the feature is implemented on our x32 versions. Microsoft has come up with a system called PatchGuard on x64 Windowses that will not allow rootkits to exist in their current x32 form.
However, the virus scanner will perfectly detect and remove rootkit-like infections that don't use hooking methods on 64bit environments.
If you have any other questions regarding this, please do not hesitate to contact us again.