If you are doing wireless to wireless via the router your 2 machines will interfere with each other. You should get better than 250k though.

I would first try the obvious and plug them into the router and see what you best case is going to be. If it is still this slow then you know you have a application issue.

A good tool when you control both ends of a connection is a very old tool called IPERF.
It is a line mode command that will test transfer rates and let you adjust various TCP settings. Since it is a very simple tool it can test the network without any overhead of the machines it is running on.