Dual Channel Memory query

Hi guys,

I have an Asus A8V board, AMD64 3700+ San Diego cpu and the following memory :

2 x 1Gb Samsung PC3200
2 x 256Mb Samsung PC3200

Can I use all four and still access dual channel mode? (2 x 256Mb in blue slots and 2 x 1Gb in black)

If not would it be better to have 2.5Gb single channel or 2Gb dual channel? From what I've read the performance increase for dual channel is minimal on AMD64 chips.

Thanks!

yes but i found that i get MUCH better performance with using only 2 modules.