As an addition to MRDEVIOUS's comment I will add a link to a site where you can download a brainwave generator programme (free) and it helps ppl to meditate, sleep, think or just CHILL.
I have it on my pc and it helps in so many different ways.
Here goes: http://dl.winsite.com/bin/Info?2529

Hope it works.

P.S It does work with win XP also