we know that Kimimaro's abilities were stronger then Uchihas - this includes Itachi as Sasuke has more potential, and to prefer Kimimaro over Sasuke means hes pretty damn strong.
We'll never know exactly how strong because of the illness though but think of it in this way, Sasuke has been said to possess more potential then Itachi - so if hes only a SECOND choice, imagine how damn strong Kimimaro could be.



</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE </td></tr><tr><td id='QUOTE'>Itachi is the strongest character in the series so far. No buts and ifs about it.</td></tr></table><div class='postcolor'>

Kabuto fought Tsunade, Shizune, summoned Manda and two snakes and then took a rasengen in the stomach and STILL SURVIVED TO FIGHT ANOTHER DAY.

we&#39;re yet to see what Kabuto can really do, he has a history of playing down his abilities (failing the genin exam 3 times, chuunin exam 6 times) and refering back to his eyes in the forest of death we can see that theres something big coming.

As for Itachi - Kakashi said he was yet to show us all his powers BEFORE he used the Mange Sharigan, Zabuza has also beaten Kakashi with one move, just like Itachi beat Kakashi with Mange Sharigan.

In terms of mystery over their exact extent of powers Kabuto is unknown

as for all those people that use the defence &#39;Itachi was too tired to fight Jiraiya&#39; look at what Kabuto did and compare.
</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE </td></tr><tr><td id='QUOTE'>Kabuto fought Tsunade, Shizune, summoned Manda and two snakes and then took a rasengen in the stomach and STILL SURVIVED TO FIGHT ANOTHER DAY.</td></tr></table><div class='postcolor'>