I approve of this Johnobi movement. I'll also take this time to supplement Johnny's anti-WoC tactics with the following, derived from my experiences with the army:
1. Frenzy-bait his Chariots. Ld8 still fails a significant amount of tests, and getting those things stuck on a block of Zombies or hurtling off the board after smashing up some Wolves is far better than letting them complement his already-formidable blocks.
2. The Marauders you can try and deal with in one of several ways. First would be to take advantage of their Frenzy and make them expose a flank. Charging in with a base or two of Spirit Hosts accomplishes this rather admirably, especially given how poorly protected Marauders are (just keep 'em away from Knights). Next, a speedbump (like 5 Dire Wolves) at an angle can get you that same flank, though it won't always give you the same amount of time to maneuver into a situation to exploit it.
3. Consider either beefing up your Black Knights' numbers, or swapping them out for Grave Guard. While some may find this to be a bit controversial because GG give up the movement edge, I've always found that GG deal MUCH better with Chaos than BK's, and the main reasons why are that striking at Initiative with Lances still means you're going last (so the great disadvantage of Great Weapons falls by the wayside), and those extra numbers come in very handy against someone who goes first and can crack open the armor save of BK's. Not saying it'll be a cure-all, but I think it'll help. Just remember to bring a lot of them.
4. Pick at his characters. His L4 may be a pain to get to, but you can definitely gank the L2 next to him, and all you have to do in that front is get a cheap Necro in the same unit as your Vampire Lord to cast Spirit Leech, so you can use his unmodified Ld10 on it. Incidentally, this is one of the reasons I favor a foot Lord - you can have a couple of Necros hanging around trying to pick off the important guys, especially when you have an army in Chaos that HAS to come to you.
As to how I would implement these changes, I'd axe the Skeleton Warriors, and replace them with lots of Zombies and Dire Wolves. Next, I'd bid a tearful farewell to the Varghulf, and install 3 x Spirit Hosts in its place. Any leftover points would be well spent either adding a rank of Black Knights, or outright replacing them with a Horde of Grave Guard. I personally would go for the GG, but maybe I'm underestimating BK a bit. Put your VL in the Ghouls along with a Necro or two, then put some Hero Vamps in the GG. Those changes should give you two fighting units he can't just run into blindly (as for your preferred matchups - Ghouls into Marauders, GG into Warriors or Knights), as well as a means to deal with his pesky characters.