We [Microsoft] tend to have quite a few diamonds in the rough. One of those is our DLL Help database. This is a public tool where you can search to see nearly all of the public releases of a specific file. For example, if you are having an issue with a Microsoft product and have it narrowed down to a DLL, EXE, or SYS file, then you can look it up to see if there are newer releases of it and/or what public release the file was installed by. Anyway, here is the location of the database.
Microsoft DLL Help Database
The disadvantage of this database is that it doesn't always show *all* of the public releases such as hotfixes. For that you need to search the Microsoft Knowledge Base for the file name located at: