count files in a directory

[rbt]

I assume that there's a better way than this to count the files in a 
directory recursively. Is there???

def count_em(valid_path):
     x = 0
     for root, dirs, files in os.walk(valid_path):
         for f in files:
             x = x+1
     print "There are", x, "files in this directory."
     return x

rbt