LOL!!
Look, you seem to be under the impression that any task can be split an infinite number of ways to achieve an infinite speedup on an computer with infinite cores. This is not the case.
Most tasks are not embarrassingly parallel. And those that are are generally better done on the GPU.
The Athlon II is slower clock-for-clock, core-for-core than the Core architecture. With single-threaded performance being the bottleneck for so many things an Athlon II quad is not likely to buy you a day.
While true, 4x is nowhere near infinite, and games are most certainly doing good at using them
(using them well doesn't need a 4x speed-up v. 1 core, it just more of a speedup than having fewer cores). An Athlon II may be slower per-clock, on average, but not by enough to matter. You can basically compare them at clock parity: large cache C2D/Q v. PhII x2-4, small-cache and/or low-FSB C2D/Q v. AII x2-4.
The Athlon II X4 really has just a very tiny market -- those who need a basic PC but perform some task that can occasionally load four cores.
For anyone who really needs the cores, shelling out an additional $20 for the 955, $80 for the 1090T or ~$140 for the i5 is the smart buy.
Hence Llano and Brazos. With the new Pentiums, the Athlon II's last bastion of usefulness has finally been infringed upon. Unless you run POVRay or similar, IMO, the 6-core PhIIs are just too much, compared to SB i3 and i5 CPUs.
As it is, throw a nice new GPU (not necessarily fast, just
new), and a bit more RAM, into a Core 2 or Stars box that's a few years old, and maybe upgrade the HDD, and you will have fixed the ills of most such systems.
Today, big vendors are stills selling S775 boxes. As in, today, there is still enough new demand.
Personally, I think the Core 2 CPUs will last another 3-5 years, provided minor upgrades are done to the systems.