I think you can find all these by going to Control Panel - Sounds.
If you select the sound of interest it will show you where it is.
I think the directory is called Media.  Or, if you just get the file
name, you can alsway use Windows Explorer "Find"
to locate the file.

The files are .WAV format, at least the last time I looked.  
They used to be 8-bit WAVs but I suspect they've all changed
to 16-bit now.

Hope this helps!

Bob Masta
dqatechATdaqartaDOTcom

           D A Q A R T A
Data AcQuisition And Real-Time Analysis
          www.daqarta.com

The sound files used by Windows should be in C:\WINDOWS\MEDIA. The sounds
for other applications might be in their respective programs folder.
Usually those are wave files (.wav).

Wave files are actually sounds and midifiles (.mid)are synthesisers
commands. Why do you want to convert them to MIDI?

Some professional audio and midi sequencers (musicians programs) attempt to
include some utilities to do that but that does not work if there is more
than one note at the same time.

If you manage to convert them, all you will get are commands (ex: play a
note for x beats at such intensity on that channel). I don't think that
would be very usefull with Windows beeps and clicks.

Dominique