I'll add a little more weight to my reasoning so as to avoid being labelled as an AMD fanboi, which no doubt will happen.
The Penryn architecture benefits from extra L2 cache. Compare, if you will, the 9400 (2.66GHz, 6MB L2) to the 9450 (2.66GHz, 12MB L2 cache). Same core, same FSB, just more cache.
http://www.anandtech.com/bench/Product/76?vs=51
In any test that works well with lots of cache (and with L2, it's much faster than going to L3), the results are up to 19% faster in places, but on average, the gains are not substantial. Note how much the SYSMark 2007 - Overall result is skewed by the Productivity score (the very same 19% I mentioned earlier). Intel CPUs utilise an inclusive cache system, and as Core 2 Quads are two Duos bolted together, this would in essence point to 6MB that neither package has to share with the other. AMD CPUs employ an
exclusive architecture which allows them to use less cache, however there's a sizeable penalty incurred in looking for data. Throwing more L3 cache at the Phenom II was a big help but it's far slower than having a large area of L2. Notice that Llano uses 1MB of L2 per core and enjoys an IPC advantage over previous K10.5 designs under most workloads even without having any L3 cache at all. I'm sure L3 helps in some circumstances, though.
So, let's change the comparison...
http://www.anandtech.com/bench/Product/81?vs=76
For obvious reasons, let's ignore SYSMark.
CS4 - traditionally strong on Intel CPUs. 18% faster.
DivX - Intel 7% quicker
x264 - 1st Pass - AMD 4% quicker; 2nd pass - Intel 8% quicker (AMD never do well here)
WME - no difference
3dsmax r9 - too many to calculate
but more wins for Intel than for AMD, not a large difference overall
Cinebench R10 - tiny win for AMD, could be within the realms of natural variability between tests
POV-Ray 3.7 Beta 23 - small win for Intel
PAR2 - AMD 5% quicker
Blender 2.48a - Intel 23% quicker, big win
Monte Carlo - Intel 42% quicker, traditionally strong test for them/weak for AMD
Sony Vegas Pro 8 - AMD 3% quicker
Sorensen Squeeze Pro 5 - Intel 8% quicker
WinRAR 3.8 Compression - AMD 16% quicker
Games average - Intel 5% quicker (Far Cry 2 - an amazing 27% quicker for Intel, but the others show a negligible difference (small AMD win in Fallout 3))
The 920 has a 133MHz advantage plus the "benefit" of L3 cache, however there's little evidence that really helps here for most tests. More L2 cache than 512KB per core may have been a lot more useful.
You'll notice that Intel doesn't sweep the board. Yes, Core 2 is faster, per clock, in most scenarios, but not noticably, and certainly not dominated as you claim. Far Cry 2 was developed by Ubisoft
in conjunction with Intel. AMD seems to be very good in WinRAR and relatively decent overall at video compression, but falls down with Excel 2007, Blender and CS4 which also appear to be optimised very well for Intel architectures or Stars is just plain bad at them.
In the end, there's very little difference between Penryn and K10.5 at similar clock speeds for the majority of tasks (albeit with a limited testing suite to go off), and if a processor does something rather well, it makes more sense to buy that one. If you want a more rounded CPU, the Core 2 Quad would make more sense in this circumstance, but far too often you'll find that they're priced far too much, definitely so for the 12MB L2 cache models.
Time for an unfair comparison:
http://www.anandtech.com/bench/Product/146?vs=48
A $1,000 (at least) QX9770 being beaten in most tasks by a 1090T, but like I said, it's unfair as the AMD part has 6 cores and Turbo Core. IPC aside, in this case it'd be madness to own any Core 2 product for productivity, but the Core 2 Quad is a more consistent performer across the board.
Neither you nor I truly know how Bulldozer is going to perform yet.