Is there anyway to clone partition to partition in windows 7 for free using some kind of command line tool so that i can set block size to increase speed

i google and found some tools like dd for windows and dcfldd but when i use them it gives me error like access denied and permission denied i tried to login as administrator using: net user administrator on but its same problem

dcfldd bs=4096 if=.\k: of=\.\m:

while its working to create image file :

dcfldd bs=4096 if=.\k: of=\.\M:\filename.ext

some help needed on this will appreciate thanks