Stay Live 2000 keeps your Internet dial-up connection active and online by periodically sending a small TCP/IP packet to one of the atomic clocks maintained by the United States government. Sending these packets prevents your ISP from dropping your connection due to inactivity.
I recently up-graded one of my computers to Win. XP from '98. For some reason my Dial-up connection dropped more frequently with XP, so I tried this program. Now I can download large files without worrying about losing my connection.