windows 7 how to change the os language

mm dont think its that easy to get hold of a copy of Win7 and take it you didnt get a copy with your acer. they usually expect you to copy files from the pc with i think 3 disks.

As said take it to your local pc repair shop they should be able to tell you/show you how to change it - if your lucky they wont charge you. Alternatively ring them and explain - they cant charge for info
I should imagine its as easy as going to the clock region language and changing your location from spain to UK/Ireland

ok found this on windows help

Install or change a display language

You can change the language Windows uses to display text in wizards, dialog boxes, menus, and other items in the user interface. Some display languages are installed by default, while others require you to install additional language files.

There are two types of language files:

Windows 7 Language Interface Packs (LIPs).* Windows 7 LIPs provide a translated version of the most widely used areas of the user interface. LIPs are freely available to download. For more information, including a list of languages available, go to the Microsoft Local Language Program website.

Windows 7 language packs.* Windows 7 language packs provide a translated version of most of the user interface.

Before you can install a display language, you need access to the language files. These files can be found on your computer, a computer in your network, or your Windows DVD. They can also be downloaded from the web. For more information about the differences between language packs and Language Interface Packs, and how to get them, see How do I get additional display languages?

Note
Language packs are available in Windows 7 Ultimate through Windows Update as optional updates. They aren't installed automatically. If you're using Windows 7 Enterprise, contact your system administrator for information about installing additional languages.

To install a display language
To install a Language Interface Pack (LIP), double-click the file to open the setup program. To install a language pack, follow these steps:

Click to open Region and Language.

Click the Keyboards and Languages tab.

Under Display language, click Install/uninstall languages, and then follow the steps. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.

Note
The Display language section will be visible only if you have already installed a Language Interface Pack or if your edition of Windows supports a language pack. Language packs are available only in Windows 7 Ultimate and Windows 7 Enterprise.

To change your display language
When you change the display language, the text in menus and dialog boxes for some programs might not be in the language that you want. This happens because the program might not support Unicode. For more information about changing the text in menus and dialog boxes for programs that don't support Unicode, see Change the system locale.

If you want to set the display language for multiple users or for the Welcome screen, see Apply regional and language settings to reserved accounts.

Click to open Region and Language.

Click the Keyboards and Languages tab.

Under Display language, choose a language from the list, and then click OK.

Note
If you don't see the list of display languages, you need to install additional language files.

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Change your keyboard layout

You can customize your keyboard for a specific language or format by changing the keyboard layout. The layout controls which characters appear on the screen when you press the keys on your keyboard. Some input languages have several keyboard layouts; others have only one. For example, you can change your keyboard layout from the English QWERTY format to the English Dvorak format. After you change the layout, the characters on your screen might not correspond to the characters on your keyboard keys.

Before you can change the keyboard layout, you must add the input language and keyboard layout that you want to Windows. For more information, see Add or change an input language.

To change the keyboard layout
On the Language bar, click the Input language button, and then select an input language.

Language bar

Click the Keyboard layout button, and then select a keyboard layout.

Note
If you don't see the Language bar, right-click the taskbar, point to Toolbars, and then click Language bar.

To change the keyboard layout on the Welcome screen
On the Welcome screen, click the Keyboard layout button , and then select a keyboard layout.

Note
If you don't see the Keyboard layout button, you might not have more than one input language, or your regional and language settings might not be applied to reserved accounts. For more information about reserved accounts, see Apply regional and language settings to reserved accounts.

take a look at these screenshots and follow down as i should imagine everything is is the same order