I assume, that the processor that you mention is the X4 955 BE.
For the mobo try to get the M4A79T Deluxe and DDR3 4GB. Also, a better GPU is an option.
What is the principal objet of the rig? Games, surf the web, video edition....
Given us all the specifications.
1- CPU
2- GPU
3- RAM
4- HDD
5- MOBO
6- PSU
With this parts, here in the forum can help you a little more.