You have to remember that AMD and Intel have different socket types.
The way i see it,without upgrading the motherboard and messing everything up, youd have to upgrade from intel to intel.
If your looking for more of a budget type processor Intel does not have any 64-bit architectures with which to support 4 GB of RAM.
You'll have to go a bit more expensive to get support for your 4 GB of RAM. Try not to go to expensive unless you have the money.