Best processor for m3a78-em

Hello and welcome to the forums
First of all,I edited your message,because you don't have to post your e-mail in public forums
About your question,which specific model do you have?
ASUS M3A78-EMH,ASUS M3A78-T,or the Pro version ?

I had the same set-up, I upgraded to a X4 940, but that board can take almost any AMD CPU all the way up to a X6 1090t... all it needs is the latest BIOS.. to run the X6

Check my set-up out its in my signature I have the M3A78-CM which is practically the same board as the M3A78-EM except for the type of onboard graphics