Beginner looking at a friends Nikon D200 or micro 4/3?

You should also consider which system you want to buy into.  You will likely buy a flash and a lens or two (or ten, if you post more on dpreview!).  When you change bodies, eventually, it would be a good idea to buy in the same system so that you don't take a loss switching systems.  So, look at the lenses and types of bodies available in each system and determine which provides the best upgrade path for you.