URL rewrite module can easily do this kind of rewriting, however it requires that the hosting provider has it installed and enabled.
If your hosting provider does not have official IIS URL rewriter module installed then an alternative solution is to use one of the an open source .NET url rewriting solutions such as URLRewriter.NET. In order for it to work with IIS 7.0 integrated pipeline mode, register the module within <system.webServer> section as follows:
<system.webServer>
<modules>
<add name="UrlRewriterNET" type="Intelligencia.UrlRewriter.RewriterHttpModule, Intelligencia.UrlRewriter" preCondition="" />
</modules>
</system.webServer>
The preCondition attribute is important here. Setting it to emtpy string ensures that the module will run for all requests, not just requests for managed handlers.