Dual Core CPUs excel at doing more than one task at one time. For example, if you have a DVD movie running and are running some other program at the same time, a single core CPU can often be brought to its knees. Intel alleviated this somewhat with something called Hyperthreading by having the CPU act as two logical units. Two processor cores in an AMD Dual Core CPU allow the same functionality.
Oblivion is one of those games that make you just sit back and say WOW at the beautiful graphics. The game takes a decent CPU to run, as it stresses the whole computer system. I was not able to discern a big difference in the game with the 5000+ and the 4600+. This game uses the video card to a big degree and the CPU while contributing to the performance; it is not the biggest factor.
Power draw on the 4600+ on our test system was very respectable. Under load on the test motherboard it drew around 150W of power for overall power of the entire testbed. The 3800+ on the other hand drew around 125W of power total. When compared to the 5000+ on the regular AMD M2 platform, the power draw was almost 200W. When considering the performance difference, the energy draw is excellent.