Hi again, guys, and thanks everyone!
Well, I managed to install it at last. The problem was very simple (and curious), as the only thing I had to do is inserting a graphic card in the PCIe slot... (The GFX unit was integrated in the motherboard, so it had no additional card).
I did that and it worked perfectly...
IcAROS is fantastic, I get to load ADF games amazingly and it's a really atractive OS, though a little unstable sometimes and VERY difficult to set it up... I think IŽll never make Internet work in this desktop...
The only flaw is when trying to run Workbench applications... Only a few of them work :-( Well, I can't understand very well in the manual the procedure to run everything in coherence mode (I guess this makes WB aps to be run in the same Icaros desktop) and the only I managed is to run those aps in another screen (Wanderer?) through Janus, but, the mouse pointer moves like flashing, imprecise if you are, for instance, making some pixel art, and Octamed does not run at all, Deluxe Paint always crashes...
I want to know how to make everything run in the Magellan desktop, as I think performance will be better than running in another screen at the same time.
The fact is that, when running in WinUAE in this same computer, it runs very very fast, so I don't know why this happens :-(