Xcopy not working from System.Diagnostics.Process.Start()

This one wasn't easy.

See http://social.msdn.microsoft.com/Forums/en-US/netfxbcl/thread/ab3c0cc7-83c2-4a86-9188-40588b7d1a52/

"This is a quirk of xcopy.exe. If you redirect the output, you have to redirect the input as well."