get the new motherboard as it will have better functions than the one you got.you could use more ram,but what is there is good enough for the time being.the nforce2 chipset does support dual channel so you will see a performance gain just from that.anyways,go with the new board and worry bout the other stuff later.
evga nforce4 sli ready mainboard
X2 4400+dual core cpu
2X1gig samsung ddr400 in dual channel mode
evga 7800gt video card
wd 300gig hd