Oh and another tip:
There's a sign in the entrance of nether wich says I made it a bitsome easier.
I plan to do it, but I didn't finish this til now, so you turn on peaceful AS SOON AS you hae killed one ghast (ghasts are those

flying ... things)
because I want to delete all the GHAST-spawners and than let only one GHast stay in nether.
If this will not be possible I plan to make a trap at the spawner wich makes that the spawner gets destroyed (by a single TNT-block) as soon as the first GHAST leaves
that's because I think this Ghasts are really cool, but when the player has to fight many of more than one or two of them down it would be to hard...