Hi, my name is Steve Ball and I'm a Principal Program Manager Lead on the Windows Sound Team. I'd like to take a moment and give some background on sound schemes in Windows as well as the new sound schemes released as Ultimate Extras and their relationship with the default Windows Vista scheme.

Default Windows Vista Sound Scheme
The default Windows Vista sound scheme was designed with the same principles that were used in designing the Windows Vista visual elements and desktop experience.  In contrast, the Windows XP sounds, while appropriate at the time and for that product design, were very ‘Western' and literal, using pianos and western orchestral instruments.   The XP sounds were designed to complement the ‘photo-realistic' Bliss desktop (blue sky, green grass photo.)  The Windows XP sounds can also be rather percussive and jarring in the context of day to day PC use, so it was an explicit goal to re-orchestrate the default Windows Vista sounds to complement the softer, cleaner theme and user interface elements in Windows Vista.  

For Windows Vista, it was an intentional design goal to avoid ‘reinventing' the User Interface language for sound.  For example,