Microsoft has no URL rewriting module for any version below IIS 7.x. This will mean your URLs are like yoursite.com/index.php/about-us rather than yoursite.com/about-us.
However, if you do want friendly URLs you must you must buy or use other URL rewriting software:
* [IIRF](http://iirf.codeplex.com/) (should work for most cases - see [IIS 6 guide](windows-manual-iis-6) for rewrite rules)
* [ISAPI_Rewrite](http://www.helicontech.com/download-isapi_rewrite3.htm) (The freeware, lite version should be fine for simple installations)
* If you have 64-bit Windows, you can try [this](http://www.micronovae.com/ModRewrite/ModRewrite.html)
Instructions are available for [installing PHP on IIS 6](http://learn.iis.net/page.aspx/248/configuring-fastcgi-extension-for-iis60/) by the IIS team.
On Windows XP, you need to disable **Check that file exists**. See [installation-on-windows-pi](windows-pi) for more information.
Matthew Poole has expanded on these instructions [with a tutorial](http://cubiksoundz.blogspot.com/2008/12/tech-note-installing-silverstripe-cms.html).