Indeed I was thinking about it. The only problem is that I'm down here in Brazil, so the price for 4 gigs of pc6400 is around 190-230 local.
And it looks like I can't find the pc5400 anymore, so I'll probably retire that memory and stick with this mobo and memory for another 2 years or so. So far the bottleneck of my system is my graphics card, but I can still replace that and stick with processor and decent memory.
Thanks a bunch