some clarifications and additions:
1: not all Dual Channel RAM's are ECC (someone else has corrected it, thanks)
2: they arent special, you an use any standard 2 similar sticks to enable dual channel.
3: Dual Channel is charecteristic of Mobo, not RAM's. it happpens as in older boards, if u r on single channel board (here i'll quote example of PC3200) that has Data Transfer rate of 3.2GB/s. so in single channel boards, if u have 2 slots, adding 2 X 256MB of similar sticks will make total ram 512MB, but Data Transfre Rate (DTR) remains 3.2GB/s. as in Dual channel mobo, if you add 2 similar Modules, it will double the amount of Memory to 512MB (Agreed) but at the same time will double DTR to 6.4GB/s..Got it?
4: as far as N-Force3 is concerned, although having three slots. doesnt meanas u have to install 3 modules to enable dual-channel. 2 makes dual channel work perfectly. but u have to install the DDr's in 2 blue banks to enable dual channel, rathe than installing 2 in close banks. similar case is in my 875p chipset, having 4 banks, 2 would have been enough to make dual channel work, still I installed all 4 banks (my requirement).
Intel Core2Quad 2.66Ghz 12MB L2-Cache
4096MB DDR Kingston Hyper-X
XFX 9600GT AlphaDog
Seagate 2 X 320GB SATA2
LG L246WH Flatron 24"