the only issue with the phenom is 2.3Ghz is MORE THAN enough for quad core games or multiple core using games. for games that will only use 2 cores properly 2.3Ghz is a "tiny" bit limiting, but most phenoms seem to do at least 2.5Ghz with ease. Mine does 2.7Ghz at stock volts on stock heatsink(haven't got anything am2+ compatible heatsink wise and spare at the mo. I'm going to try and rma the system though as the gigabyte 790fx board is horrific, its barely stable and lots of other people have found the same.
I would wait a few weeks, the B3 stepping which will have the TLB errata fix in and by all accounts should overclock better is going to ship late this month or early next month.
EVERYONE who says C2D chips are faster is correct, everyone who says they are better is wrong. You can't feel the difference between a C2D, a C2Q, a phenom or a X2 as long as they are all at say 2.6Ghz in gaming and 99% of applications, you just simply can't and anyone that says otherwise is upset about their epeen. I've had pretty much all of them so far. Sure an Intel chip right now will for sure give you higher benchmark scores, but in game theres not a lick of difference, maybe 1-2% here or there, but most games are gpu limited, and by most we're talking 99.9999999% or them.
Frankly a £60 790x chipset board and a £125 quad is something intel CAN'T match as yet. Probably not in the future either as they ramp up cache/cores with each new release so the cores aren't getting really any smaller. 45nm isn't in massive production yet for Intel and the large cache means the chips aren't cheap, Nehalem is going to be an even bigger core. £125 vs £160 is fairly simple maths for chips that in game will feel 100% identical.
A triple core may or may not be great, in the very few games that show a tiny increase in performance with quad over dual core, most likely a 3rd core would give the same improvement. It depends on pricing, but if you could get a triple core amd for the same price as an Intel dual core and the B3 stepping gives them the overclocking range into the 3-3.5Ghz range then they become very attractive chips.
Nothing wrong with the 3Ghz X2's either, most overclock a decent amount still, quite a lot hit 3.4-3.5Ghz which again is more than enough for almost all games released to date.