Microsoft periodically release updates under the category of "Extras" which potentially will be made available only to specific versions of Vista.

<a href="http://www.microsoft.com/windows/products/windowsvista/editions/choose.mspx">Here</a>'s the official comparison chart; I personally haven't used Home Basic, only Ultimate, so I don't know about the differences there actually are. Knowing Microsoft, the cheaper the version, the more unreasonable the limitations get.