Win2000/NT4/Novel

I currently administer a mix environment network. Recently we have been adding Windows 2000 workstations. The workstations see the network fine but when copying from one network drive to another the Win2k machines are alot slower then the NT4 machines. Moving the files is faster, only copying seems to be effected. Also when compiling the programers who are trying to get the license from our server have to wait awhile if their running Win2k. I had experienced similiar problems before andi just added the nt server to the host file and it speed right up, however this does not seem to work with 2k. Any dvice would be apreciated