Really interesting article. Well done
if you run the task manager, can see that Winrar integrated benchmark really do not use 100% of CPU with more than 2 processors. A Phenom II X3 710 runs 80 %, and an I7 with Hyper Threading, runs less than 50%. (I guess WinRar is memory bottlenecked, since is so sensible to memory speed).
Since Winrar does not use 100% CPU, another program running in parallel should not give it a big hit, beacuse haves unused resources.
The same should be true about Quad cores doing far better than X3 on games + AVG. Since games looks like not taking much advantage from the fourth core, it should be free for another program, and it should be the reason that AVG does not impact as heavily as tree cores.
About the AVG in background: I think that the worst inpact is the disk access. A SSD should do much better.
I own an i7 920+DDR3 1600+GF8800GT under Win7 RC and altought far cry2 integrated benchmark shows 70 fps on a given instant, is easy to see constant freezes and jumps, because Win7 does a small annoying write to disk frequently. It stops the game 0.20 seconds (to say a number), and in the remaining 0.80 second, it does 70 frames. It benchmark as 70 fps, but the 0.20 delay reduces experience as if where 4 fps.
most benchmarks lies.
I guess that the quad core more a SSD will do far better with AVG in background.