hi my last project i finished it succesfully an SP35P2 PRO XPC shuttle, but at the end not enough cpu power and memory 11G cpu and 8 gig memory ...so a new project i found and SH55j2 XPC with yes here it starts a realtek RTL8111E onboard.
now my question is i found somewhere the with creating an oem.tgz for the rtl 8111D it all works but is the rtl8111D the same as rtl 8111E ?? i don t have the case in house yet. but i will come back on this. and then for the CPU i was thinking about a CORE I7 875K that will end i think between 18-24G cpu power. and want to give it 16GIG memory (ddr3 1333) that would be enough for me i think.

are there any suggestions on what to do. for example the onboard nic which worrys me.

You'd probably be Ok with the driver, but if you have a spare slot I would stick in an Intel Pro 1000.

For a new system I would look at 24 GB of memory if you could but it'll depend on what you plan to run.