Buy any intel original motherboard based on the 915G chipset. Or you can try to get boards from 3rd party manufacturers like Asus, Gigabyte, MSI, etc. All of them will come below your budget of 6000. On other thoughts, if you up your budget a little (say 500-1000), you can get some boards based on the Intel 945 chipset.
By the way, I do not understand why you want a AMD based board when you have a good intel processor. If at all you want to dump the presscott, then your choices will be something like MSI RS-480M2 or Asus A8N-E or Asus A8N-VM, but in no way you can get the processor and board combo for below 6000. The above mentioned boards alone costs in the range of 4500-5500.