A quick Google will tell you that this has been discussed plenty of times before, but seeing as I stumbled across it of my own accord today, I thought I'd give it a mention.
Set the property (the title of this post) to false, then display the dialog on a Windows 2000 machine. Whoops, the "New Folder" button is still there. Oh well.
Apparently it works on Windows XP - I guess you just have to live with it if you're running Win2k.