Windows 8 allows you to change the language (including the keyboard) if you go into the keyboard settings. You will need to know enough English to get into the settings and add the keyboard. You can then add the Spanish keyboard and keep the English keyboard as well (I believe the hotkey to switch between keyboards is Win+space).
Note: this will only change the actual input in Windows. If you want the physical keys to have Spanish letters, you'll need to buy stickers!