Many people think that Orochimaru got his ass handed to him by the 4 tailed Kyuubi. This is not true. The thing is, they were equal the whole fight. Orochimaru countered every single one of Naruto's attacks and Naruto countered every single one of Orochimaru's attacks.
On top of that, Orochimaru was sick, which people seem to forget. Not only that, but Orochimaru also found the battle fun.
So sick Orochimaru = 4 tailed Kyuubi