Trying to build a range of computers and have been looking at some new motherboards that can use dual channel (DDR 400) memory.

Read some good messages hear and was just wondering if I could clarify a few thoughts.

Will a DDR400 dual channel memory stick run on any DDR400 rated motherboard (even one's that are not dual channel rated like SIS 648FX based mobo's?

For dual-channel capable mobos (like the Asus p4c800 delux Intel 875P based board I believe) are two sticks necessary for dual channel to work?

Is dual channel enable by default if I put the sticks in the odd slots?

Finally, some of the dual channel memory I've seen have built in heat sinks while others do not. Are the heat sinks necessary or are there true differences between the various manufacturers chips?

thanks

"Will a DDR400 dual channel memory stick run on any DDR400 rated motherboard (even one's that are not dual channel rated like SIS 648FX based mobo's?"
There is no such thing as dual channel memory. There is regular DDR memory that is tested in pairs with a dual-channel motherboards to verify that the pair has close enough timing specs to run in dual-channel mode. Certain brands and model DDR memory work better with certain motherboards. You have to research a particular motherboard to see what works best. Usually the manufacturer will give a list of compatible memory. Other memory might work. You have to search computer forums to see what others have tried. If you try just any DDR memory in dual-channel mode your experiences might range from works great to no POST. It is up to you.

"For dual-channel capable mobos (like the Asus p4c800 delux Intel 875P based board I believe) are two sticks necessary for dual channel to work?"
Two sticks are necessary. Dual-channel means two memory controllers on the motherboard. An example is the ASUS A7N8X Deluxe which has three memory slots.
Slot 1: Controller 1
Slot 2: Controller 1
Slot 3: Controller 2
As you can see to take advantage of dual-channel mode two sticks are necessary with one stick in either slot 1 or 2 and the other stick in slot 3.

"Is dual channel enable by default if I put the sticks in the odd slots?"
You need to put the sticks in slots controlled by different controllers. Which ones depends upon the motherboard. See the previous answer for an example. If you do this dual-channel is automatically used.

"Finally, some of the dual channel memory I've seen have built in heat sinks while others do not. Are the heat sinks necessary or are there true differences between the various manufacturers chips?"
The heat sinks cool the memory by about a degree celcius. There use seems to be more a matter of personal preference.