In fact this is the first time I think Apple have released a new generation of machines which were actually slower than the previous generation - the tests over at barefeats (http://www.barefeats.com/macvpc.html) showing even the dual 2.5Ghz G5 out-performing the dual 3.4Ghz Xeon in 4 out of 6 tests.
That barefeats test is an older one, comparing a G5 with the Xeon from 18 months ago that doesn't share much with the current chips apart from its name and the ability to execute x86 instructions -
http://www.barefeats.com/quad06.html is the comparison of an actual 2.66Ghz Quad (new)Xeon powered Mac with the previous model Quad G5. That new mid-range Xeon Mac walks all over the old top of the line Quad G5 in everything but PPC Binary performance... ie running PPC-only apps. Pity, as most of the reason I'd want one is to run Photoshop, and it's not Universal yet
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However like the older PPCs which seemed slower at release, as soon as those apps shift to native code for the CPU they're running on, that'll change to line up with the other benchmarks. At release, an 80MHz PPC601 had trouble justifying itself against a 40MHz 68040 as almost no PPC coded apps existed, let alone a fully PPC OS. As soon as the PowerPC started running native apps it won by a long shot.
Dana
