I am currently still in my testing phase. I am using 2 routerboard 112 with sr-9 cards plugged in. I have each unit connected to 900 MHz antennas in the same room for testing. I have a computer connected to each board and I am interfacing with the boards via winbox. I can tell that the units are connecting to each other when one is set to AP and the other is a client. I am currently using only the software that comes with the routerboards. I can obviously get each computer to talk to its routerboard and I can get the radios talking to each other. The problem I am having is that I can not get the computers talking to each other via the radios. I have all of the gear on the same subnet and as far as I can tell, all of the networking settings should be right. My next thought is that there are limitations to what you are allowed to do with the free software that comes with the units and that I need to try testing with 1 of the licensed packages.

Generally MikroTik RouterOS comes preinstalled to the RouterBOARD, it comes with license level4, Level4 does not have any limitations you are talking about,
http://www.mikrotik.com/software.php

To create transparent network over two wireless routets use WDS,
http://wiki.mikrotik.com/wiki/Transpare ... o_Networks

Have you setup your routing / firewall rules?

If not, try the easiest firewall rule: go to IP/Firewall/NAT, and add a SRC-NAT rule with action masquarade. Remember to set both pc's to use their MT's as default gateways.

Then you should be able to ping from PC -> PC.

Also remember, you are now routing, so PC1 and MT1's ethernet side should have the same IP range, MT1 and MT2's Wireless should have a different IP range, and MT2 and PC2's ethernet should also have a different range, otherwise routing wont work.

Hope this helps!