dual proc system and memory

hoping someone here can help me out.

i'm building a system based on an article from TH;
http://www.tomshardware.com/2005/11/07/single/

i've got the board (asus k8n dl) but have some questions about ram. the board has 6 slots, 4 for 1st cpu and 2 for 2nd cpu. i'm going to be using 2 opteron 248's with the board. anyway what i'm wondering is do i need to get 4 chips to start (2 512 registered for cpu1 & 2 512 registered for cpu2) or can i do something like 2 1gb for cpu1 and 2 512 for cpu2), letting me upgrade later by adding 2 1bg to cpu2 and moving the 2 512's over to cpu1 so i would have 2 1gb & 2 512 for cpu1 and 2 1gb for cpu2.

i work with a lot of graphic programs, so i am inclined to get as much memeory as i can afford. any suggestions, i'm a bit overwhelmed by all the different info i keep finding.

that's what i've been thinking, will mean i need to put my build on hold for another week. any suggestions for ram, crutial, corsair, kinston etc...?
another question would be ddr v.s ddr2? i don't think this mombo requires ddr2, but would like to get the best possible for this setup, 4x1gb would be great but a high $$ tag, esspecially with ddr2.