The folder is used to store windows updates information.
You can delete the entire folder, it will recreate itself when you next visit windows updates.
However a few things you should know first.
If you delete the SoftwareDistribution\DataStore folder you will lose your update history.
Any updates not yet installed will need to be redownloaded.
To delete the folder you have to stop the Automatic updates and BITS service temporarily then restart them afterwards.
This subfolder $NtServicePackUninstall$ is required to uninstall your service pack, so if you plan on doing that you will need to keep it.
Read around a bit before you decide to delete it. http://www.google.de/search?q=C%3A\WI...lient=firefox-a
Hope this helps,