Hello,

Is possible to install linux in a routerboard? I have used openwrt with metarouter but I'm asking if I can install linux as if the routerboard would be a pc.

thanks in advance

Possible, but not very simple. For some RouterBOARD models there are ready made OpenWRT builds, check their site.

Possible, but not very simple. For some RouterBOARD models there are ready made OpenWRT builds, check their site.

Wrong.
There is no "ready made" builds as no mikrotik hardware is "officially" supported by OpenWRT by now.

If you have some luck, some models are in the "work in progress" state, and may really be usuable "out of the box" (like 450G).
The good point is, if you have some linux background, thanks to the good openWRT documentation you can generate your own openwrt initramfs image and netboot it very simply to test openWRT without doing any harm to your current system.

Anyway, start here; http://wiki.openwrt.org/toh/start#mikrotik