Intel has been pounding the living daylights out of AMD with its Nehalem processors, especially the new Core i5 and i7-800 models. In response, AMD has retreated to lower and lower price points, culminating with the recent release of multi-core processors priced below $100.
We're talking not just about the quad-core, 2.6GHz Athlon II X4 620, which stills sells for only $99. AMD now offers the triple-core, 2.9GHz Athlon II X3 435 (just $89.99 at Newegg) and the Athlon II X3 425, whose three 2.7GHz cores will only set you back $78.99. Throw in a motherboard like Gigabyte's $79.99 GA-MA770T-UD3P, and you've got a very cheap little multi-core rig.
Athlon II CPUs don't have L3 cache, so they may not quite catch up with their Phenom II brethren. Still, at those prices, they don't have to—the cheapest triple-core Phenom II costs $119, and AMD appears to be discontinuing it. The Athlon II X3 435 looks particularly interesting, because its 2.9GHz clock speed should give it enough horsepower to perform well in poorly multithreaded apps like games. When that extra core kicks in, you should be able to outrun competing dual-core processors without much effort, as well.
If you're not in the market for a new CPU, then we suggest you take a gander at our last deal post. That $400 Acer ultraportable with a dual-core Celeron processor, six-cell battery, and Windows 7 Home Premium is still an absolute bargain.