You can change the system code page using the Control Panel. The following instructions are for Windows 8. The hard thing in Win 8 is finding the Control Panel. If you found it, select Language. (If not complain, and I will add a link here too.)
You should now see something like this.
Please click Change date, time, or number formats (sic!) and select the Administrative tab in the appearing dialog Region.
In the box Language for non-Unicode programs you find what we are looking for. Just click on Change system locale...
If you are sure, click Apply
and choose the desired. Click twice OK, and you are done.
The good news: You do not need to reboot to make this settings effective. But you should log off, and log in again.
Start the Control Panel, and open Language. In Windows 8 the settings we are looking for are located on two tabs. On the Formats tab you find settings for date and time formats.
On the Location tab you set your current location.
In Windows 8 you can change the display language of Windows. The screenshot shows a system with four installed display languages: English, German, Japanese, and Chinese (Simplified). The Enabled one is in this case English, so all Windows dialogs are in English language. You can install additional languages, by following the Add a language option.
The good news. You only need to relogin after changing the display language to become active.