Download MKV Converter Studio 2.0 for free.  Valid on 6/6 only.  Here is a screeshot for your reference.  Scroll down a bit to see the download link.  Be sure to review the included readme.txt file before installing it.  This software converts Matroska Video (mkv) video files to various other formats, including AVI, WMV, MP4, H.264/AVC, and more so that they can be played on various devices, such as iPod, PSP, PS3, Xbox and many others.