Joss Nix

import os

folder_paths = ['./']
dst_file1 = '1.xls'
dst_file2 = '2.xls'

for itemFolder in folder_paths:
    listFiles = os.listdir(itemFolder)
    for itemFiles in listFiles:
        if (itemFiles[-4:] == '.xls'):
            size_file = os.stat(itemFolder+'/'+itemFiles).st_size/1024
            if (size_file > 200):
                os.rename(itemFolder+'/'+itemFiles, itemFolder+'/'+dst_file1) 
            else:
                os.rename(itemFolder+'/'+itemFiles, itemFolder+'/'+dst_file2)

Если вообще в лоб

в folder_paths указать пути нужных папок ['./', './newFolder', './newFolder2']