Well I went out and bought the 4" smooth schedule 40 pipe. I was concerned w/ putting that much rock on the corrugated stuff and collapsing it. From all the reading I have done and the information I have gotten on this site, I am going to put the holes downward. I will have a trench with good slope and then line it w/ the landscape fabric, then a layer of 1" washed limestone, then the perforated smooth pipe, then back-fill w/ more washed limestone. On the top layer I think I may use some smaller decorative rock, and make a walkway on the top.