CPU or Hdd upgrade?

WD black is a great hard drive. i would get the 8350

The vast majority of games only use 2 cores. There are a few that can use more than 3 core, but they are a tiny drop in the bucket compared to games using 2 cores.

There are even fewer games that can use more than 4 cores. BF3 in multiplayer mode can probably do it and probably ARMA 2 as well. How well do those games effectively use more than 4 cores is unknown at least to me. Meaning what is the actual performance increase going from 4 cores to 5 cores? Going from 5 cores to 6 core?

If playing games is the primary purpose of this PC, then most of the time 6 out of 8 cores will just be idling. 4 core will be idling when you play games capable of using 4 cores. Games capable of using 4 cores are rolling out, but unless you make it a rule not to play any game (no matter how good it is) unless it can support at least 4 cores. When you play BF3 and ARMA 2 then most likely 6 cores will be utilized and only 2 core will be idling. Using all 8 cores in games? Ummm...... I'm pretty sure you are going to replace the FX 8350 before that happens.... unless you hold on to it for maybe at least 8 years???

Get a ssd with 120/128GB or the FX-8350, it's an upgrade, the fx-6100 is a poor cpu, from the failed bulldozer architecture, the FX-8350 is a good cpu, the best from amd from the piledriver architecture, it can rival the i5 in some stuff...

You will see more improvement in performance by getting a better CPU or by upgrading to an SSD. Since you "don't want to spend an arm and a leg on SSD because (you) have alot of games (you) play and still need a lot of space" then the best upgrade is the FX-8350. You will gain zero appreciable performance by upgrading the hard drive to a 1TB.