Snippet for web.config to make a AJAX 1.0 site work with a .Net 3.5 site.
<configuration>
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.
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<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.5.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.5.0.0" />
</dependentAssembly>
</assemblyBinding>
</runtime>