HotFix

Usually downloaded from MS or through windows update, they come in the form of exe's cab's and files. Basically all they do is replace existing system files with new versions in order to patch bugs. They're called hotfixes because they can be applied individually, as opposed to installing a service pack. I recommend staying up to date with them as Windows is very prone to attack...w2k isn't bad though, not bad after sp4, most of the holes have been patched.