In my humble opinion, your money is better spent buying Dark Crusade and Soulstorm. Why both? There's this little mod called Firestorm over Kronus, which makes Dark Crusade at least twice as awesome in multiplayer.
They're expanding it soon into Firestorm over Kaurava, for Soulstorm.
So what does this mod add? A detailed list would probably be too long to post here, but here's the essential bits. Ever faction rebalanced, the combat system retooled to more accurately reflect the tabletop rules while still maintaining the gameplay style. A few other things changed are that units can now only reinforce near by listening posts and transport vehicles, similar to Dawn of War 2, same with wargear, but I think you can only upgrade that near listening posts.
New units and models? Too many to list. The Imperial Guard for examples gains access to some inquisition units, and Grey Knight Space Marines, which are pretty awesome. Black Templars are added as an independent faction on their own, and are also pretty awesome. Chaos is no longer just Khornate; you get access to a Chaos Undivided army list, with the option to choose a God to specialize. To be more clear, whereas before you basically only had Chaos Marines, Khornate Berserkers, and a few other variations. In Firestorm over Kronus, you get access to Plague Marines, Rubric Marines, and Noise Marines, along with a lot of other relevant units to go along with them.
The Nightbringer is now an HQ unit for the Necrons, and the Necrons now gain and use requisition like any other faction.
I think I've made it clear, it's a complete overhaul, and incredible. Get it.