I am using Samba to connect out windows pc to RHEL5 .
We have a one file that we shared with some users. I have already set the CHMOD of the file to rwxrw-rwT so that non-owners users can access , read and write/modify the file but cannot delete it . With this CHMOD + t setup non file owner in Windows Desktop connecting in SAMBA cannot delete the file in windows delete option or in DOS command 'del'.
The problem is that if the non-file owner users in Windows is using copy-paste they can over write the shared file by pasting a file with the same file name which is basically the same as deleting the file and replacing with another . Any suggestion please. thank you.

Problem is that you've allowed content modify (w) on that file, which means ANY content, inc none or a complete replacement.
Either you want this or you do not. If not, then no-one should be allowed to (w)rite to it.

You need to think carefully about exactly what you want to achieve; there's no way to say people can only modify a bit of a file, its meaningless.

(More accurately, to do that, you'd have to write your own access program or use eg a DB)

Sir , on Linux a file with rwxrw-rwT Sticky bit set-up follows what it is suppose to do , that is if i am not the file owner i can not delete/replace/rename the file but i can modify the content of the file , this i have tested with a text file and logging on as different user in linux . My problem is if i log to the shared folder using Samba in a windows workstation ,the windows although can not delete/rename the said file it can replace it using paste , is the problem samba or linux , any suggestion please . thanks.