http://www.q4os.org/
There are not many things for free in this world :-) but Linux is one of the best gift for humanity !
This spin of Debian is for me the best I have found, and I'm searching for a long time believe me. It's running well even on very old PC P4 - 1.5GHz/512Mb RAM/ 20GB HDD, and seems to be very stable and fast enough for day by day office work.