I recently purchased a MT 230 board with PoE & power supply. Our HQ preconfigured it and sent it to us. However, I cannot seem to connect to the unit. The unit powers up normally over the PoE supply, but when I use an Ethernet cable to connect to my laptop, no network connection shows. What is the problem? Do I need a cross over cable? I've tried only with straight. Any other way around this problem?

P.S. If I had a serial cable I would have tried.

For connecting two Ethernet devices directly you normally need a cross-over cable (read: if not at least one of the two support Auto MDI-X, or "auto-cross-over").
If you don't have a cross-over cable you could plug the RouterBoard and your computer to an ethernet switch or hub.