If you’re sick of seeing the “Add to Windows Media Player list” or “Play with Windows Media Player” options in your right-click context menu on media files, then you can just do this:
regsvr32 /u wmpshell.dll
(entered at command line or start->run). This basically just unregisters the shell extension stuff and removes those options. If you want them back, just remove the /u and re-run it.