If you’re setting up your wix install as part of an automated build, with NaNT, here’s a quick way to set the MSI Product Version attribute. In my case I’m having CruiseControl.Net run my builds and so I use this bit of NaNT XML to make sure that the MSI version is the same as the CCNET build version.

<if test="${property::exists('CCNetLabel')}">
<xmlpoke file="${build.rootFolder}\Product.wxs" value="${CCNetLabel}" xpath="/wix:Wix/wix:Product/@Version" verbose="true">
<namespaces>
<namespace prefix="wix" uri="http://schemas.microsoft.com/wix/2003/01/wi"/>
</namespaces>
</xmlpoke>