Checking Installed Updates From A Batch File

[vafox]

I'm trying to put together an "update all" batch file, so I need a way of checking the following from the command line:

1. Service Pack Level (ie: check if XP SP1 is installed)

2. DirectX Version

3. Windows Media Player Version

4. Specific hotfixes

I noticed that most hotfixes updates create a registry entry that can be checked for, but I'm not sure about the SP version, directX version, and WMP version.

Any ideas?