Hello I still have my old motherboard M2N-E Socket AM2. I just found out that the Phenom II 4 945 is now supported. How much of a performance decrease will I get from using my old M2N-E with the limited HT of 1000Mhz (2000 MT/s) from a motherboard that has a HT of 2600Mhz (5200 MT/s)? WITH NOT HAVING DDR3 IN THE MIX!!
In regards to the HT question, it wouldn't be too much of a performance hit. CPU clock speed is more important than HT speed. You could consider the CPU to be slightly crippled until you can afford a newer mobo.
The difference between DDR2 and DDr3 likewise would be negligible although the higher speeds available with ddr3 would probably help any overclocking efforts.
Like Xaira says, check the thermal rating to be sure it will work.