Change language keyboard problem

I use an Inspiron 700m with WIN XP Pro version 5.1.2600.

I have been having problem to set up the keyboard properly to change languages automatically, when I need to.

I use both English and Spanish languages.

Although I get the language bar on the taskbar with both languages, if I set up Spanish as default language, when I click on EN (English,) the keyboard does not change. The same thing happens if I setup English as default and click ES (Spanish.)

Is there any way to fix this problem?  If so, please be specific in which way do I have to manage it. Thanks!