1. go to Start menu
2. select "control panel"
3. select "language and regional"
4. select the language you want (in the pull down arrow)
a. Click OK
5.Close all your windows
6. Open your word processor: "word," "word perfect," etc. (in the bottom right hand corner you should see "English (US)" to change it...)
7. Press Shift-Alt at the same time (now it should say "SP for Spanish (Mexico, Spain, etc)
8. Start typing. The keys are:
"[" plus a letter will give you the accent mark over that letter for example: [a =á  [e =é
"=" gives you ¿
"+" gives you ¡
":" gives you ñ (shift ":" gives you Ñ)
"shift [" will give you ü, Ü

(you'll repeat steps 6-8 every time you want to use the  Spanish keyboard.)
(you can switch between Spanish and English any time) 

You can change your setting to any language you want.

II. Second Options: Change the key board
1. go to Start menu
2. select "settings"
3. select "control panel"
4. select keyboard (you'll see a new window)
5. select "input locals"
6. go to "properties"
7. select the language and click OK, OK
8. Close all your "setting windows"
9. follow steps 6,7 and 8 from option # I

good luck