What are you trying to convert? (e.g., .MOV to .MP4) What device will you play the file on? Are you dealing with a corrupted file that won't open?
While newer versions offer more formats, many users prefer v2.70 for specific reasons: Format Factory Old Version 2.70 Free Download
Despite its age, this version handles the heavy lifting for most daily tasks: Converts MP4, AVI, 3GP, RMVB, and WMV. Audio Pro: Easily swaps between MP3, WMA, AMR, and WAV. What are you trying to convert