I already answered, I know it's not the answer you wanted to hear but it's the truth.
It's very improbable to run a working version of windows, gui-ed or not without loading the registry. The registry tells windows where all it's components are and how to use them, in essence it's the backbone of the operating system. Without it windows doesn't even know where run32.dll is, which launches EVERY exe, including mame. Also the registry helps windows understand hardware, so if by some miracle you would be able to safely remove the registry you would have the same 2 gig problem again.
When you do a step by step confirmation and choose not to load the registry it's for debug purposes only... it really screws up how windows works not to load it, even if you are only running a dos prompt.
Sorry