USB diabling on 2003 AD network

I am facing a small problem that relating to desabling USB devices in AD network. What i want to do is disable USB for all computers except for some users. So i created an ADM file for disabling USB and pushed through GP. Thats working fine. And for enabling the same for some users i created a startup-script and applied to user properties. But ths script cant run because it need admin prevelege to apply to registry.

What I can do now? please give me some expert help. Is there any way to run scripts using system account prevelege?

thanks in advance