P5 under WinXP on 2.4GHz processor with 512M RAM - Yann Hair appears to freeze while adding objects, but is actually very busy. It continues and renders OK after 30 minutes or so (there are many, many objects to add!) I found I couldn't render a second time (within an hour) unless I closed P5 down and started it afresh. This problem may have disappeared with the latest SR2 beta, but I haven't had time to try it. In short, Yann hair works with 512Meg but you need to be very, very patient. David.