Dell Poweredge sc420 mainboard/processor

I've been using the sc420 as a desktop for some years, it is all I require for now. I would like to upgrade the processor with a Pentium 4 670 3.8mhz, but this processor is 64bit and 2mg. The chipset model is e7221 according to Dell, the motherboard is model 0x3468, the present processor is a P4 2.8mhz, 32bit, 1mg. How can I find out if it will work? Thanks, Ron