Roxy Music

When you slow down the Windows-95 startup sound by 4000%, it becomes 2.5 minutes of dreamy, ethereal, ambient music. 

Regular version:

Slowed version:

The sound was composed by Roxy Music’s Brian Eno (who created 84 micro-compositions on his Mac before choosing this one), and his well-known, ambient work sounds eerily similar to the slowed down version.

Source