[Udpcast] Reliability - MD5sum's don't match

Hi, I wonder if someone could help me. I have started testing the UDPreceive/udpsend programs for rolling out linux onto refurbished PC's for a charity I work for. The idea is to role out linux onto 10-20 refurbished PC's (at once) before shipping them to charities/schools/colleges that really need them, mainly in Africa. I am using the command line version because we are not transfering a raw disk image we are transferring a tar'd tree and preparing the machines for custom hardware detection (as all the hardware is basically random). The tar file is about 1.2gig, and I am piping the output through both md5sum and tar to extract it. When I tried this on 1 machine everything was fine but today I tested it onto 5 machines in parallel and the MD5sum of the result on all 5 clients did not match the server version (they did however match each other) and the tar file appears to be slightly corrupted (though the machines did boot ok). So my question is "is it possible that the data is corrupted during multicasting?" and if so "Is there anything I can do to make it work reliably?" There seem to be quite a few error correction parameters available, which ones should I try first? Any help much appreciated, Matt.