asus a7n8x dual channel question

I have an asus a7n8x board.
Currently I have a 256mg pc3200 dimm in slot 1 and another 256mg pc3200 dimm in slot 3.
From what I understand slots 1 and 2 are one channel and slot 3 is the other channel.
My question is:
Can I put the two 256mg dimms in slots 1 and 2 and put a 512mg dimm in slot 3 in order to create 512 mgs on each of the two channels total?
I cant afford to scrap the two 256mg dimms I have for 2 512mg dimms so I figured if I just add one 512 mg to one side of the channel and the two 256mg dimms to the other side I will have 512 on each side. Will I still be utilizing the dual channel or will it slow down my PC.

I came across this thread at Nforcehq.com a couple days ago, and according to them it should work.
http://www.nforcershq.com/forum/viewtopic.php?t=38578

yup, it tells you in the bios manual you can do that. You should notice a 3-5% bandwidth increase, but it will work.

Yes,it works. as long as you have the same amount of memory in each channel it will work just fine.

What brand ram are you using? This is a picky board, and it better not be generic ram, or else you might not get over 154 mhz

Im not ;(