Q6600 is the spiritual successor to the ABIT BP6 Dual Celeron option: https://en.wikipedia.org/wiki/ABIT_BP6
My latest ASUS was good enough, but I didn't (and probably won't) build any newer systems, so ABITs will have the crown.
I seem to recall that only Quake 2 or 3 was capable of actually using that second processor during a game, but that wasn't the point ;)