I actualy think Kabuto is stronger then Oro, i actualy think he is the 2nd strongest character introduced so far.
Although there are some theories that support it a little (chuunin exam) Its just a feeling I have.
We dont know what kishimoto has in store for us, but I think Kabuto is way stronger then we think. It seems that Kabuto has like atsasuki (or something never got the name right) a big interest in the development of naruto and he doesnt seem to care about sasuke. But unlike atsasuki I think kabuto has intrest in naruto and not just kyubi.