Is there such a thing as an AM2+/AM3 motherboard that can use DDR2 and DDR3 simultaneously with an AM3 CPU? (I know it would be impossible with an AM2+ proc as they don't have DDR3 controllers). It would be great for inveterate upgraders like me, but a Herculean feat of electrical engineering.
No. Jetway makes one that has 2 ddr2 and 2 ddr3 slots, but you can't use both at the same time. The model number is MA3-79GD6. Directron sells it for $94.99. It is a micro atx board. Jetway has recently improved their website, but right now it's very slow to download.