In IIS 7.5, I'm trying to rewrite a Url such as /about to /content.asp?p=about, with support for QueryString-s, so if the orginal Url was /about?x=y, it should rewrite to /content.asp?p=about&x=y.

The basic rewriting is now working, but when I'm trying to add a QueryString it doesn't work. Tried both /about?x=y and /about&x=y.

My current rule:

<rule name="RewriteUserFriendlyURL1" stopProcessing="false">
    <match url="^([^/]+)/?$" />
    <conditions>
        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
    </conditions>
    <action type="Rewrite" url="content.asp?p={R:1}" />
</rule>

How can I fix this?

Thank you.