For Athlon 64 X2: MSI K9N Diamond
The K9N Diamond was not included in our last Socket AM2 motherboard roundup, but the K9N SLI Platinum was. (It technically is the little brother of the two, using the nForce 570 SLI chipset). The K9N Diamond runs Nvidia's nForce 590 SLI chipset, which is the high-end chipset product for AMD processors.
This motherboard is available at $160 and up, and thus offers a great price/performance ratio for a product that targets the upper part of the market. It comes with a total of six Serial ATA/300 boards, two x16 PCI Express slots for dual graphics operation, two 32-bit expansion slots, dual Gigabit Ethernet, Firewire-1394 ports and a motherboard cooling solution that uses both a heatpipe and an active fan. Dolby Digital is supported and there is a coaxial digital audio output as well. If you also go with a MSI graphics card, you can make use of MSI's automatic overclocking mechanism for the motherboard and the graphics card(s).