I have installed a compatible driver for OpenGL but I'm still getting this error:

      Bad video card drivers!     
      -----------------------     

Minecraft was unable to start because it failed to find an accelerated OpenGL mode.
This can usually be fixed by updating the video card drivers.

--- BEGIN ERROR REPORT 7fe0271 --------
Generated 1/20/11 10:15 PM

Minecraft: Minecraft Beta 1.2_01
OS: Windows XP (x86) version 5.1
Java: 1.6.0_23, Sun Microsystems Inc.
VM: Java HotSpot(TM) Client VM (mixed mode), Sun Microsystems Inc.
LWJGL: 2.4.2
[failed to get system properties (java.lang.NullPointerException)]

org.lwjgl.LWJGLException: Pixel format not accelerated
    at org.lwjgl.opengl.WindowsPeerInfo.nChoosePixelFormat(Native Method)
    at org.lwjgl.opengl.WindowsPeerInfo.choosePixelFormat(WindowsPeerInfo.java:52)
    at org.lwjgl.opengl.WindowsDisplay.createWindow(WindowsDisplay.java:185)
    at org.lwjgl.opengl.Display.createWindow(Display.java:311)
    at org.lwjgl.opengl.Display.create(Display.java:856)
    at org.lwjgl.opengl.Display.create(Display.java:784)
    at org.lwjgl.opengl.Display.create(Display.java:765)
    at net.minecraft.client.Minecraft.a(SourceFile:280)
    at net.minecraft.client.Minecraft.run(SourceFile:643)
    at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT 282a4ea0 ----------

Any ideas?