Athlon 64 - Which motherboard and memory?

Hello

I recently posted a query about overclocking my Asus A7V333, and received
very useful advice (thanks Kony and Sleepy).
I however reckon, that in the near future I'll be looking to upgrade to an
Athlon 64 set-up, probably starting at 3200+ level, but with a view to
upgrading to Athlon 64 FX at a later stage.

I have the Gigabyte K8NSN XP 939 in mind, but would be obliged for any other
suggestions.

I also note that the motherboard supports Dual Channel DDR 400 PC3200
Is the Dual Channel DDR worth the extra expense? If so what brand? I would
anticipate fitting two 512mb modules.

Thanks
John Hellingsworth