Windows 2000 quota assignment

Hello,
Please bare with me im a beginner in windows 2000 server. I just enable quota on one my disk and the problem is that once i put a 50mb limit on one folder for one user i was able to put more 70mb without having an error message. I am not sure how it is working in win2k but in netware one i limit the user for 50mb it will prompt for error.

Also one thing on the list of quota entry i found out that the 50mb is assigned to user administrator even the user who is log doesn’t have any decrease in size.

Please help/.