Meanwhile, a recent 50%-off Steam sale for Dawn of War II spurred sales of Relic's tactical RTS, pushing it to the top of the Valve charts. Digital preorder sales for NCsoft's MMO Aion also remain strong, capturing top spots on both lists.

Steam's top 10 sellers for the week of 7/26 - 8/1:

1. Warhammer 40,000: Dawn of War II
2. Aion: Collector's Edition (Preorder)
3. Left 4 Dead
4. Counter-Strike: Source
5. The Secret of Monkey Island: Special Edition
6. Killing Floor
7. Company of Heroes: Tales of Valor
8. Team Fortress 2
9. The Orange Box
10. ArmA 2

1. The Sims 3
2. Warhammer 40,000: Dawn of War II
3. Champions Online (Preorder)
4. Aion (Preorder)
5. East India Compan
6. ArmA 2
7. Dawn of Discovery
8. The Sims 3 (Mac)
9. Civilization 4: The Complete Edition
10. Fallout 3