One thing to keep in mind is that the cheapest dual core is $300 while the single core Opteron 144 can be had for as little as $135 (the price seems to have fallen a lot recently). For a gaming oriented computer, I would only buy a dual core once the graphics hardware has been more or less maxed out. That saved money could be put into the video card, which would yield a
much larger boost over any processor you could buy.
Can't comment on the stock cooler though. I just slapped my XP-90 back on. Figure I'll send the opty heatsink with the winchester if I ever get around to selling that thing.
That's exactly what I did.

Although my 146 just came with the crappy basic cooler.