They contain uninstall info for Windows updates. They are only needed if you need to install those particular updates. If you don't think you'll ever have to uninstall these updates, you can safely delete them all, except ONE: $hf_mig$
You can also delete the following:
- Contents of the C:\WINDOWS\ie8updates folder (but not the ie8updates folder itself)
- Contents of the C:\WINDOWS\SoftwareDistribution\Download folder (but not the Download folder itself)
- Text files starting with KB in the C:\WINDOWS\ folder.
I always delete the above with no problems at all. G