I want to provide some clarification regarding the Windows Installer 3.1 requirement for the newly released SMS 2003 Inventory Tool for Microsoft Updates. This tool provides integration with the Windows Update Agent and the catalog of updates available on Windows Update and Microsoft Update to enterprise customers.
You may notice that the tool has a requirement on MSI 3.1. This is due to the fact that MSI 3.1 is considered a mandatory update in the Windows Update world. A mandatory update is basically a required update to get the full functionality for detecting and deploying MSP-based updates through the Windows Update Agent. Windows Server Update Services (WSUS) has a hard requirement on MSI 3.1. This means that no clients will be offered any updates until MSI 3.1 is installed on the client computer for WSUS clients and home computers using Automatic Updates. On my home machine, I delayed installing MSI 3.1 just out of pure laziness for several months. When I finally did, there were over a dozen updates applicable on my machine that I had not been aware of because the mandatory MSI 3.1 update had not been installed. WSUS clients will automatically get MSI 3.1 before any patches are applied. Home users are advised to install MSI 3.1 as part of the automatic updates process.
In the enterprise, with SMS and the new inventory tool, the story is slightly different. SMS does not force an update or upgrade to MSI 3.1. In fact, you will still be able to scan machines *successfully* even with MSI 2.0 on the managed client. I have to clarify what successfully means. This means that the scan will not fail. However, you will not receive update detection and deployment information for any MSI-based updates. This includes the CAB's MSP files that Microsoft Office uses to deploy updates to Office XP and Office 2003. You will get no errors, no warnings, no nothing. Updates will simply not be shown as applicable, because the MSI API's that the Windows Update Agent relies on simply are not there in older versions. It bears mentioning that in the future, many more products at Microsoft will be jumping on the Microsoft Update, affectionately known as MU, bandwagon. If these product teams use an MSI-based servicing model, you will also not receive an accurate applicability status for those updates. Bottom line: You might not know what you are missing in the future.
So let's talk MSI 3.0 vs. 3.1. If your clients are running MSI 3.0, you will actually see successful scan results for all clients. However, I strongly encourage you to upgrade to MSI 3.1. Several critical fixes were made that make this a valuable update and one that is well worth deploying.
One other thing to point out. The Windows Installer 3.1 download center page documents the latest version as 3.1.4000.2435. However, if you run msiexec from the command line, the listed version is 3.01.4000.1823. This is perfectly fine and the correct version you should be seeing. The msi.dll version is the actual version that is reflected on the download center page.
So, with my official Microsoft hat on, I say update to the required, mandatory, important and highly useful MSI 3.1. If you call product support and request assistance with MSI 2.0 or 3.0 or otherwise need a hotfix, you will be asked to first update to MSI 3.1. So that is the official support for MSI. But go ahead, read between the lines, and make your own informed decision that is right for you regarding the upgrade to MSI 3.1.
Feel free to send comments or e-mail me.