viperguynaz

found the answer – I followed the instructions here – http://learn.iis.net/page.aspx/280/install-wordpress-on-iis/

First I downloaded and installed URL Rewrite 2.0 – http://www.iis.net/download/URLRewrite

Then I added the following to the web.config file in the WordPress root:

<rewrite>
    <rules>
        <rule name="Main Rule" stopProcessing="true">
            <match url=".*" />
            <conditions logicalGrouping="MatchAll">
                <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
            </conditions>
            <action type="Rewrite" url="index.php" />
        </rule>
    </rules>
</rewrite>

And all works now!