Captcha image - ASP.NET

Why roll out your own captcha when reCAPTCHA is free, accessible (through the audio option, making it usable for people with visual issues) and at the same time helps digitize various publications? There's even a .NET implementation.

Edit:

Seeing how it's for fun, having a look at "An ASP.NET Framework for Human Interactive Proofs" might give you some good ideas. Especially the ImageHipChallenge as it includes image distortion code examples.

For example:

for (int y = 0; y < height; y++)
{
    for (int x = 0; x < width; x++)
    {
        int newX = (int)(x + (distortion * Math.Sin(Math.PI * y / 64.0)));
        int newY = (int)(y + (distortion * Math.Cos(Math.PI * x / 64.0)));
        if (newX < 0 || newX >= width) newX = 0;
        if (newY < 0 || newY >= height) newY = 0;
        b.SetPixel(x, y, copy.GetPixel(newX, newY));
    }
}

Which will move the pixels in a wave like fashion. Such as in the second word of your example.