This is my first English post. Hurray!

So, if you have a Sony Ericsson G900, you probably want to load it with media. Music is easy, but video is harder. It can't natively play AVI/DiVX, which is most of the media you can find online.

Luckily, you can easily convert almost all media types to its native MP4 with MPlayer. Here are the few steps you need to take to be able to convert videos to the G900's MP4 format:

1. Get MPlayer's Windows binaries here. There are newer builds, but I found that they are still buggy, and this build worked for me. If you find something newer and better – Let me know!
2. After you do that, open the archive to some folder, say, C:\Program Files\MPlayer, and navigate to that folder. Note that the files will reside in a subfolder called "MPlayer-1.0rc2". Get them into the main MPlayer folder (Enter the MPlayer-1.0rc2 folder, Ctrl-A, Ctrl-X, Backspace, Ctrl-V).
3. Open a command prompt (Start=>Run=>Type "cmd"=>OK), and then paste this text in the window that opens:

   echo %0\..\mencoder.exe %1 -v -ofps 25 -of lavf -lavfopts format=mp4 -af lavcresample=44100 -vf expand=:::::4/3,scale=320:240,harddup -oac lavc -ovc lavc -lavcopts aglobal=1:vglobal=1:acodec=libfaac:abitrate=128:vcodec=libx264:vbitrate=384:keyint=25 -o "%~dpn1.mp4" > "C:\Program Files\MPlayer\ToG900.bat"

   Note: If you unpacked MPlayer into a different folder, change the path that's marked in red at the end of the line.

4. Now you have a file called "ToG900" in your MPlayer folder. You can drag and drop video files onto it and their MP4 version will appear in their original location (Note – The conversion takes time! Be patient). You can also choose it when right clicking the video file and choosing Open With. Just browse for it…

Good luck!

(Based upon this that I found here)