The bad news just doesn"t seem to end for Yahoo. As the Internet portal prepares to fend off a proxy fight by billionaire investor Carl Icahn, new research from comScore concludes that for the first time, Google has overtaken Yahoo as the most-visited Web site in the U.S. Google reached the pinnacle of the Top 50 U.S. Properties in April, with an audience of 141 million visitors, according to data from comScore"s monthly analysis. Yahoo and its affiliated sites ranked second, with 140.6 million visitors, followed by Microsoft sites with 121.2 million visitors.