参见这个地址，使用htc来处理png，特点如下：
- Automatic activation of transparency for PNGs in the page.
- Support for <IMG SRC=""> elements.
- Support for background PNG images (unlike many other scripts!)
- Background images can be defined inline or in external stylesheets.
- Automatically handles changed SRC/background via normal JavaScript (e.g. mouseover rollovers) -- no special coding needed.
- Change support includes CSS 'className' changes on elements.
- Incorporates automatic workaround for <a href=""> elements within PNG-background elements.
- Tiny script (for fast downloads).
- Licensed under a Free Software license.
下载地址：http://www.twinhelix.com/css/iepngfix