|depending on your login system couldnt you just use the >> drex96log.txt|
so for example
if your username variable is username
(im assuming that you are prompting for a user name something like
set /p username="please enter your user name :"
echo %date% %time% >> C:\yourdosfolder\drex96log.txt
echo %username% >> C:\yourdosfolder\drex96log.txt
this will create an ongoing log, entitled drex96.txt where ever you direct it
the >> will add instead of deleteing your information.