here is an old version of my network diagram if you wanna see how i did it.  Need to update it though, have added many things since then.

GLIFFY?!

MOOSE!  Why didn't you tell me about that?!  I downloaded Visio and wasted at least a week trying to figure out how to make a network map, and come to find out it's that easy?!  

Ok i tried making good use of my DMZ. I have a very limited knowledge on diagrams, but please tell me what looks wrong. thanks 

the way he has it is fine.  generally from what i have read DMZ should hang off the main network router, before an actual firewall since anything should be able to access those devices, however some rules still apply.

another thing i notice, with as many workstations as there are listed, your hanging the entire network off a single switch.  what happens if that switch goes down??? everyone will lose internet access.  Same goes for router, does it have enough bandwidth for 100PC's plus webtraffic and such?

is this design hopefully gonna go into production somewhere, apartment complex/business?  try and include as much detail as humanly possible, will make your life easier.  Heck when i laid out my recent network topology i filled like 4 sheets of paper with details.