To answer your question, first, keyboards can be English, French, or Bilingual.  From what you said, it sounds like you have a bilingual keyboard and your machine is set to English.  When you have your computer set to English, the those accent keys do not function and should be ignored.

Normally, computers are set to the language we type in most.  When we want an accent key it is usually quicker to insert the character by way of using our ALT key and a number combination.  The most popular accents and that process of how to do it, is
discussed further on the following page, http://www.ercomputers.com/Ascichar.html

However, if you do a lot of French typing, you can add French to the computer so that you can change the keyboard language by clicking on a button in our taskbar or using shortcut key combination.  You should understand that the characters that were on those keys will be moved somewhere else on the keyboard.

How we add a keyboard is as follows.  First put your Windows CD in your CD-ROM, wait a few seconds and close any window that opens before you start.

Once that is done, click on the button, go up to Settings, then Control Panel.
There you will find the Keyboard program.  Double click on it.

When the dialog box opens, choose the Language tab at the top of the window.  The language your computer keyboard is set to is listed.

Choose the Add button, yet another dialog box will open.  There is a list of languages you can choose from.  Choose the French (Canadian) keyboard, then click on the OK button.

You will be back in the Keyboard properties. Make sure there is a check mark beside 'Enable indicator on taskbar'.  This will let you switch back a forth easily.  Once you click on the OK button, notice there will be an  En  added on the right of your taskbar (near your clock, if it is on).

When you want to change the language, single click on the  En  and choose the  Fr  keyboard.  Repeat the process when you want to return to English.

I hope this helps clarify your question...