Looks like you needn't wait for dual core chipsets/mobos and CPU's. From reading this Anandtech article they won't be worth waiting for at all:
http://www.anandtech.com/cpuchipsets...oc.aspx?i=2377
Multi-core might be the future, but it seems initially they will simply be more expensive for the same or perhaps even less performance. So if you were to upgrade now, your motherboard would be just fine for a couple years so long as it had pci express, just might want to get a mid to low end A64 now, then in a year get a mid-range one for a fair sized speed bump.