I think that I responded to another thread you had about the alignment of the elements. As for the noise color for the captcha you can change that by adding this url parameter to the image path for the captcha:
noisecolor=
So the path to the image for the captcha on the form should look like this:
<img src="WA_ValidationToolkit/WAVT_CaptchaSecurityImages.php?field=Registration_group_Security_code&font=Fonts/MOM_T___.TTFamp;noisecolor=000000
You would then set the color you would want it to be in place of the 000000.