I really wanted this article to compare to current C2D/C2Q, but alas.
Interestingly, first desktop dual core chips were available in 2005. By 2007, some new games were demonstrating significant speed up on dual core systems.We clearly see from Crysis, Call of Duty 4, and Oblivion, that single-core CPUs now struggle in games and will at least limit the detail levels you can play at.