Remotely Manage Devices

Hi,

I have two questions I have 100 Windows XP and Windows 2000 PCs and to manage these PCs I have installed TightVNC software but everytime users change the password.

Q1. Is there any way I can change TightVNC password remotely and also hide it from so that no one knows I accessed the PC.

Q2. Is there any way I can disable Devices like USB, Sound Card remotely.

I would appreciate if someone assist me on it.

Thanks and Regards.

Anurag.