Since you are worried about licensing, but you correctly are trying to avoid Access... This is hardly and optimal solution, but what about another instance on the same server. You can put limits on it to try to keep it masked off from your production instance. Limit it's memory and keep it down to a single processor. That'll also allow you a bit of leeway in terms of security. It's not perfect, but I think it'll work out better than putting it on the same instance as your production data.

Move to 2008 then you can put the Resource Governor to work along with some policy based management.