Networking without MT isn't going to work usefully
Erm, why?
I've seen the source code to various networked games and read plenty of articles about the architecture of others and none of them used multithreading.
I could perhaps understand a MMO game requiring multithreading, but it's overkill for a vast number of game styles.
Networking *is* hard, but there are tools to help - from low level sockets to mid level enet to high level gnet. All of these are quite usable within - and have even been designed for - single threaded environments.
So please, if you're thinking about doing a networked game, don't be put off by this!