|>> Can we do this with out sed?|
sure, of course you can use batch like what M2 posted. That's one way. (since your requirement is simple)
sed is just one of the tools out there excellent for data processing and as you can see, its just one line of regular expression. If you have more complex task other than just replacing @ and $, eg dealing with XML, exchanging text around in a file, grepping for multiline patterns, etc, using batch will be a pain. Use the appropriate tools for the job.
GNU win32 packages | Gawk