Theorycraft: Apparently your OS does the same thing so the improved speed will be either in a faster implementation or a longer caching time of the responses. If it was free I'd give it a try but not worth paying money for I'd say.
I second that. And if it caches responses longer than the OS, perhaps it caches them longer than the expiry time sent by the DNS server... that's a BAD idea.
If you don't think windows' DNS cache is good enough, google for treewalk DNS, that might float your boat. And it's free.