What many of the reviews come down to is the for the DDR3's crappy latency, it's as fast as DDR2.
This invokes thoughts of fast ram in the future.
Right now about $100 a GB is to expensive, for ram running at the same speed.
The real improvement looks to be memory controller in the P35 Chipset, 10 to 15%.
Still not enough to run out and buy a new motherboard.
Look the only reason I an buying DDR2 is that it's so cheap.
Search TOM's and GOOGLE....truckloads.
At this point in time (and I suspect as long as another 3-4 years) DDR3 systems are for fools that think the world around them will get in gear befor their MB dies of old age....much like XP/Vista 64 bit OS users who are -still- waiting for software developers to "get in line".
It's a foregone conclusion that, at the same clock speed, the memory with tighter timings will win. So if you're going to call 'same speed' as the apple you're comparing, then DDR2 will win every time.
DDR3 in it's current state is only faster than DDR2 at the highest clock speeds - i.e. where raw speed can overcome the needed looser timings. So for now, the best bang/buck by FAR is to stay with DDR2 - It's far far far cheaper, and faster at 'normal' clock speeds. But going forward - a year from now as a guess - DDR3 will improve with tighter timings and ever faster clock speeds. Plus increased production should begin to drive down the cost of the stuff. Then people will start to use it more and more.