I thought I'd chime in here, as I'm seeing some inaccurate information being posted.
Krusty I think you're a bit confused on what a "FSB" is and does, and I thought maybe everyone here might want to learn something. (And I have 20 minutes until my next meeting, so I've got time to burn...)
The "FSB" is simply an acronym for the "front side bus." (A bit of a misnomer that dates from the old days when a CPU had a front side bus and a separate bus, sometimes called the "Back Side Bus," to its Level 2 cache.) The Front Side Bus is simply the link between the CPU and its northbridge/memory controller. AMD Athlon 64 series CPUs don't have a "front side bus" by the classical definition of the term, because they have the memory controller on the CPU. What they do have is a Hypertransport 1600 or 2000 MHz (effective rate) bus to the rest of the system.
You CANNOT and should not compare CPUs with such a totally different architecture because of anything relating to "FSB." The front side bus does not have anything to do with power consumption, at all.
Power consumption of any CPU is related to its capacitance, voltage (squared actually), clock speed, and static leakage currents. The number of transistors does not have any direct impact on power consumption either. (There is a loop hole here, but that's WAY beyond the scope of this post...)
AMD Athlon 64s draw much less power because of two key features. 1. Lower clock speed. 2. Silicon on Insulator (SOI) construction. SOI reduces the capacitance of a transistor, which results in lower overall power consumption. The drawback of SOI is that it is more expensive to build chips using it.
To put it quite simply, the Pentium 4 (netburst architecture) draws more power because it requires a higher clockspeed than the K8 architecture of the Athlon 64 to achieve the same level of performance.
The Athlon 64 perform better in games because its on die (built into the CPU) memory controller decreases the latency (time to access) to access system memory. Games benefit more than most other applications from reduced memory latency.
I personally look at either CPU as a great option these days. Both are very fast and priced very competively that you really can't go wrong either way. They both have very mature and stable platforms available if you go with Intel 9xx series for Intel and nVidia nForce 4 for AMD. AMD is a bit faster for gaming if you have a very high end graphics card that can take advantage of it. If you don't spend good money ($300+) for the graphics card you are going to be bottlenecked there with either high end CPU.
My answer to the question is that unless you have $2000 to spend on the system to afford the $500 GeForce 7800 GTX 512 MB or Radeon 1900 XTX graphics card with the AMD FX CPU that the review sites are testing with you probably won't ever notice a difference.
This whole "dual core is bad/buggy for gaming" is also somewhat unfair, as this is really an issue with the operating system and games not being written to support dual core processors properly. The stutters in games will effect AMD and Intel dual core CPUs. You can make things worse though by loading special drivers (Cool and Quiet for AMD and enabling Speedstep for Intel) that change clock speeds based on CPU load, as games sometimes seem to behave badly when the CPU clock changes on the fly. The fix is to set processor affinity on the game to only use one CPU. I'd also expect Microsoft to release a patch to address the issue at some point as well.
I personally run an Athlon 64 X2 4400+ CPU on an Asus A8N32 Deluxe motherboard with a GeForce 7800 GT and am very happy with it. My laptops are both Intel Pentium M based. All of them are perfectly stable and very fast.
