Well everything you suggested was already reported on earlier in the thread, HDD specs included.

SATA 3.0gbps, 7200, 64mb, WD RE4, 0% fragmentation

Router is fine. Ports forwarded, DMZ has no effect. Processor is fine, voltages are fine, not OCed. It gets particularly bad during peak hours. During the "blackouts", there is no PC activity, S and R numbers are low, and then suddenly after some time everything just pops into place. Sometimes I'll be waiting so long for an NPC to load their text after talking to then that I will have to terminate the program in order to move again.

udubdave, can you post your system and OS specs for comparison? Maybe we have a common culprit.