Hi,
i know this is a little late, but there's an easier way to show the security tab. Open Windows Explorer, click on Tools, then on Folder Options. In the "View" tab, scroll all the way down, and uncheck "Use simple filesharing (recommended)". After that, the security tab is visible. However, it seems as if that option is unavailable on XP Home, I just thought I should dump this thought in here.
Greetz
alcaeus