Today at work I had a Windows 7 PC that was defaulted to English United Kingdom instead of English United States. I was able to log onto the PC as the customer and go into Control Panel to access Region Language. I selected English (United States) under each tab for Formats, Location, Keyboards and Languages. I rebooted the PC and noticed the keyboard was still English (United Kingdom). So a quick Google search and I found the following web link.
What I missed was selecting the Administrative tab, click the Copy settings button, and placing the two checks in the boxes. Click OK to save and then reboot. you should have the correct region and language settings for your PC.