Before we go forward, we need to define some acronyms, clear up some fancytalk, and tie everything together with a simple picture:

• Theme: A collection and configuration of elements – wallpaper, screensaver, sounds, and colors – that work together to provide a specific look and feel.
• MCT: A Market-Customized Theme is merely a Theme tailored for a specific locale (e.g. South Africa).
• Local Pack: A collection of locale-specific elements, typically links, RSS feeds, and a MCT.

Make sense so far? Well, sadly the engineers responsible for this feature complicated things with their abysmal folder configuration. Let’s untangle the mess:

• %windir%Globalization: A folder supporting Globalization services in Windows 7, such as Extended Linguistic Services (ELS), National Language Support (NLS), and Local Packs.
• %windir%GlobalizationMCT: A (poorly-named) folder containing installed Local Packs.
• %windir%GlobalizationMCTMCT-XX: Each installed Local Pack follows this (poor) naming convention. MCT-[ISO 3166 two-letter country/region code].

As mentioned earlier, each Local Pack (typically) contains a MCT and a handful of web links and RSS feeds. This translates to the contents of each %windir%GlobalizationMCTMCT-XX folder:

• RSSFeed: Contains configuration data defining locale-specific RSS feeds. These are installed into Internet Explorer upon activation.
• Theme and (LocaleName): These folders comprise of the actual MCT. The configuration file in the Theme folder dictates what folder to pull resources from, making the exact name irrelevant. In your everyday-copy of Windows 7, this name matches the locale name (e.g. United States). Themes are made visible via the Personalization applet upon activation.
• Websites for (LocaleName): Contains shortcuts (.lnk) to locale-specific/popular web sites (e.g. usa.gov). These links are copied into Internet Explorer’s favorites upon activation.

Phew. Now that you’ve been exposed to the purpose of all these files and folders, we can talk about actually using a Local Pack. In a normal end-user scenario, Local Packs are only activated when the user sets his/her location/region via Windows Setup (fresh install) or while tinkering in the Region and Language Options Control Panel applet (existing install). Power users, however, can activate and deactivate Local Packs at their leisure without dicking with permissions, an abusive method used by… pretty much everyone.

To properly tinker with Local Packs on Windows 7, make use of the oddly-named Content Management Engine Tool (mctadmin.exe). (This tool ships with Windows 7 and should not be run as an Administrator.) After issuing the desired command, check your Personalization applet for the new MCT! (Developers can use %errorlevel% within a batch to check for error.)

• To apply (install) a Local Pack, issue mctadmin /a
• To remove a Local Pack, issue mctadmin /r

TIP: If you’re unsure of what to put as a region, refer to this handy list of ISO 3166 codes.

I’m a PC and Windows 7 was my idea. Microsoft stole it, I swear.