Had an skeleton for about a year now and just in the process of taking it apart to build an i7 rig into it.
To answer the dust question once and for all, IT IS NOT A PROBLEM. sorry to go all capital on you guys, but fed up of hearing it from peeps who don't have one.
re air flow, again, a diferent concept to conventional cases. A case needs airflow as it it has to get the hot air out of thecase to the room. the skeleton doesn't have this restriction. I have been running mine previously with a Q6600 clocked at 3.6 for a year with what would normally be thought of as an incapable fan zalman CNPS 9500 LED and the temps have barely breached 45 degrees at full tat.
To answer the original question of this thread, the zalman fan fits fine with no modificatins to the case, however any of the conventional square type coolers will require a bit of cutting of the enclosures large fan cowling (but hey who's averse to a bit of dremmeling???)
I've opted for the titan fenrir to cool my i7, and will be getting out the dremmel tomorrow morning to re mod the cowling.
Just as extra info, any fan bigger than 160mm in height will not fit under the fan assembly inside the cowling, even if you chop the cowling.