I register a chinese IDN xn--a8-6k6cu57j.com and forward to my regular website, currently the http://xn--a8-6k6cu57j.com works well in both IE 7 and Firefox.
but the http://www.xn--a8-6k6cu57j.com doesn't works, anyone has some experience?
When the non-www version of your website works and the www version doesn't work (or the other way around) that is usually a caching issue. The cache should expire in a day or so.
You can use the snapshot tool to view the uncached www version of your page.
How do I access the Web Page Snapshot tool? http://www.dynadot.com/help/question.html?aid=136