depends on which processors you go with. check http://www.intel.com/products/processor/xeon/ for your processor and go from there. I purchased a poweredge 1800 from dell with two 3.0 ghz 1mb, 800mhz fsb. which can use either i386 or x86_64 distro. still waiting for 64bit manifestdestiny to finish on bt, btw.... hth, Cameron