Microsoft stopped shipping a TFTP server with their operating systems as of Windows NT 3.51, supposedly because it was not secure. (At least, they were giving security a passing glance back then.) There are many reasons why a TFTP server is important (for example, uploading an image to a Cisco device or resetting a PIX password). This tech-recipe describes a free, third-party TFTP server.
Performing a Google search for tftp server free will lead to a number of TFTP servers. The SolarWinds TFTP server has worked well for me in the past. Download, install, reboot, and you are almost ready to serve files by TFTP.
After the reboot, run the server. (Look in Start -> All programs -> SolarWinds ….) After the TFTP server window opens, click File -> Configure. The default directory for files served by the TFTP server is C:\TFTPBOOT. If you have files in another directory that you would like to serve, you can change the TFTP root directory here.
Before you can serve any files, you need to configure the server to transfer files. (The default setting is receive only.) Click on the Security tab in the configuration window and select Transmit only or Transmit and Receive files, depending on your needs. If you are worried about unauthorized access to your TFTP server, you can restrict access by IP address range in the Advanced Security tab. You can also turn on logging of all requests in the Log tab.
Once you click OK on the configuration window, you are ready to serve.