Dual channel question

[Dilzem]

Here we go i have a asus mobo a8n-vm-csm its got 4 mem banks two of them are populated with two 512 corsiar pros sticks i want to add 2 x 1 gig sticks do these sticks i want to add have to b the same type of ram as the 512 sticks or can i get away with using corsiar budjet sticks.I want to keep it using dual channel mode.Had this machine sitting there now using it as a games comp i bought a 7600gt 256mb ddr3 GFX the other day but know i need more ram