I'm not even familiar with the Pentium/Celeron/Atom lineup. I think for a performance orientated value buy, you have to go straight to $220 and get the i5 part for that price point, and stay there. The atom chip in my netbook is one of the first gen Atom parts as single core HT, and it is so freakin' slow. Clock per clock it's about half as fast as a typical Celeron (from what I've read). And clock per clock the Atom is about 3-4 times slower than my 4670k (after you divide the performance marks of the 4670k because it has four cores). It's better now but dear god, they are so slow I'd hardly call it an upgrade at all.
But then also mobile parts are not identical performance wise to desktop parts, so that's another hit.
But if you only play Wolf3d then you obviously don't need that much... Me, I do a whole lot apart from Wolf3d gaming. I use my CPU much more than the average gamer, actually. I actually degraded my chip for a good 100-200mhz from the overclock and the heavy workload.