Here's the rule of thumb on security updates:::
The $NTUninstaller$ files come with every Windows update...
They can add up to a good amount of space...but can also be gotten rid of...they are neccessary to remove a wonked update however so shouldn't be just weed whacked outta the system though just in case.
For example there was a Vista Update for instance that wonked connectivity on certain branded machines...therefore also shut down updates...the uninstaller needed to be present to run the fix MS provided. So for those that erased the uninstaller the patch wouldn't run and it added up to more work to fix...
So my method which you can choose to use...or not is after updates if everything is running fine you can safely delete the $NTUninstaller$ for those updates...i usually wait approx 2 weeks just in case.
Any of those that are 6 months old or older go ahead and get rid of.
I've also heard some folks burn them to CD just in case but i think that's pretty much ridiculous.
Hope this clarifies things...