The AMD Phenom II X3 710 is an interesting beast of a CPU. It is the second fastest triple core CPU that AMD has to offer, but the fact is you can spend a little more money on the Phenom II 720 which is $20 more expensive giving you increased speed and an unlocked multiplier, or alternatively, you can spend more money on a X4 CPU with higher performance. Newegg has the 710 on their website for $119, which is a fair price for the new CPU.
Note that if you are buying a motherboard with DDR3 support you will be forced to buy the Phenom IIs that are on the AM3 interface. This leads to an interesting situation where the fastest AM2+ CPU, the 940 is noticeably faster than the fastest AM3 CPU. As we move further into 2009 and new AMD CPUs are released on the AM3 platform, I'm sure the speeds will surpass the AM2+ platform CPUs.
One of the good things about using the AMD platform is that the new CPUs will generally work on older chipsets as the interface is the same meaning that you can upgrade the CPU on a motherboard without buying a new motherboard assuming the manufacturer has updated BIOS that supports the new CPU. This means the cost of a new platform is less than on the Intel side of things since you don't have to spend the extra money that new memory and have the expense of a new motherboard as you would on the Intel side with their new platform.
