Only have certain plugins on main blog

I guess this is more of a general wordpress question but I think it can fit in with Pro Sites as well.

Is it possible to only allow certain plugins to be used on my main blog as I do not want them viewable or usable on any of the sub domain blogs that will be created with multisite.

I guess I could set up a new level in Pro Sites and assign my main blog to that level but I do not want others to even see this level as a possibility.

What actions should I take to make this possible