We cannot forget though as mefit pointed out that the Separatists where being aided by Sidious, and of course Dooku. Without Sidious Grievous will find it difficult to execute effective strategy and will suffer from a lack of intellegence on enemy movements. He will also not have effecitvely a sabotuer on the other side. And without Dooku he will have difficulty keeping the Sepratists leaders unified and supporting him, as well as other Sepratists worlds which may abadon a cyborg leader. Most likely as the fight goes on he will be stipped of everything apart from his droids armies and his factories.
I'd like to look at the tactics of both. Both are experienced and proven generals and are very agressive. I see no clear advantage when it comes to strategy EXCEPT that MtU has Fett. With that in mind, I might give a slight tactical advantage to MtU. Also: we need to look at exactly what kind of plans are available to these guys. We need to look at their options. The bulk of Greivous's army is made up of B1 battle droids, which are only good (correct me if I'm wrong) overwhelming the enemy through numbers. MtU's army is made up of experienced war veterans. They can do many things. In this since, MtU has an advantage because his soldier type gives him more options in war. Am I making since? I think this indicates another advantage for MtU. Due to soldier quality he'll have more options and manueverability with his battle plans.
Despite these two points and the recent ones made by StarSquirrel (I think that's his name?) I still feel that Greivous will win. Just look at who he fought during the Clone Wars: an army significantly bigger then MtU's that had much better industry, and had the entire Jedi Order. And Greivous came close to beating them at times. Greivous wins this particular Kaggath due to an advantage in numbers and industry.
However he only really need the droid armies to win, he has a powerful enough force to attack Dxun and perhaps kill Mandalore if he attempts to protect it. Mandalore did after all participate in the Second Battle of Dxun during the Mandalorians Wars - he may not be so lucky to escape alive with Grievous' deadly battle droids rampaging over the moon. This is at least how I see the Kaggath heading. Fight me!