Can anyone help me? When I try to install the M assistant from this it downloads but when I try to run it it says"it needs repair please reinstall and try again " which I have done multiple times. Both trying to repair and removing and reinstalling?

Can anyone help me? When I try to install the migration assistant on my Dell PC (running XP) from this link (http://support.apple.com/kb/DL1557) it downloads and says it has installed successfully but when I try to run it it says "it needs repair please reinstall and try again " which I have done multiple times. Both trying to repair and removing and reinstalling? Is the file corrupted? or is there another place this can be downloaded? Has anyone had a similar difficulty getting this to run on a PC. Any help verrry much appreciated.