A question about renaming files

[mike]

Hi, Maybe one of you know what to do here. 
I converted some files to avi in windows. I then used ubuntu to rename the files over my network. In windows, when renaming files I never had to type the avi extention, just the name and things worked fine.
I did the same in ubuntu, just typed the new name and the file was renamed. Linux still reported it as a avi file so I thought things were fine.
   After going back to windows however, I only heard the filename and file for the file type. So windows wanted to know what to play the file with? I told it and the file played fine. 
I then added the avi extension as .avi and everything worked fine, but .avi is now reported in windows as part of the filename when I hear the name. Then it reports the file as a video clip like it should.
   My question is how do I fix this so the avi extension is not reported. Just renaming the file in windows or Linux doesn't do this. Apparently Linux does something different when files are renamed.
Mike.