Social Security payments to illegal aliens is not even a real issue. If illegal aliens have worked to pay Social Security taxes, they deserve the benefits. In most cases illegal immigrants use fake identification, which leads to the federal government collecting surplus Social Security benefits.
One of the most despicable things the Republican party has done on the immigration issue is to try and succeed politically by relying on fear of Hispanics and it is a shame to see Ron Paul take this path.
Update February 27, 2008: Here is a video of former Republican Texas Congressman Dick Armey speaking on the overinflated fear of illegal immigration.