Windows XP is the only Windows platform that still supports IE6. Support for Windows XP ends in... well, have a look for yourself here.
Global usage of IE6 is so low (outside of China) that it can be ignored without much side effects (kind of like all those low-usage browsers most people don't even know about).
In other words, the return on investment to support IE6 is way, way, WAY too bad to even think about doing it. Just drop the support and get on with your life, you'll save both time and money.