Up to 160 is actually in the normal range.
Is that just for laptops, or does that carry over to desktops too?
Also, I've noticed that the one core of my processor consistently runs a few degrees warmer than the other core.
Its the same for both, although you have to keep a closer eye on laptops because they tend to heat much quicker than desktops due to lack of proper ventilation.
As for your multi core CPU issue...I'll have to bow out of that part of this discussion. I lost touch with the latest in CPU's after the P4's came out. I know virtually nothing about the multi core CPU's. But I did a Google search on the issue and from what I've read it seems to be normal. It just means that the hotter core is getting worked a little more than the other(s)