Need dual channel help

This is a list of components I'm using for my new setup:

Gigabyte SINXP1394 mobo
400w Power supply
16x dvd
52x24x52 cdrw
100gb Western Digital harddrive
Windows XP Home
Sonic Xplosion soundcard
Geforce FX 5200
Thermaltake Spark 7 cooler
Got a 2.4ghz P4 on the way(running a 2.0ghz celeron right now)
Black/silver case, mouse, keyboard and monitor
When I get eveything together I'll post some pics..

I have a stick of Kingmax Gold Edition 512mb pc3200 ram and just bought a stick of 512mb pc3200 ram from memory-up.com(Black Diamond)- won't let me run in dual channel mode. Don't want to spend more $$$ getting a set of 1GB of memory;if neccessary will drop down to 512mb total(2x256mb) of the same type of memory. What is the best thing to do?? Should I get another stick of 1 or the other and 'hope that it works??Is anyone running dual channel with this mobo?? I might just sell both sticks of 512mb and pay the difference in getting the same brand and size, etc...Is 512mb of ram enough????pc3200 or pc3500???

It depends on your application
if you are running programs that require a lot of memory 1 gig is better.
However if that is not the case, 512 meg might be more than enough.

Have you tried forcing timings instead of "By SPD"? - make sure you arent running one or the other out of spec.