New York-Internet advertising reached $1.3 billion in spending in the first half of 2000, according to a study released late Tuesday by Competitive Media Reporting. The report shows Internet spending increased 65% from a year earlier, when Internet advertising crested at $789.6 million. Large consumer brands continued to pace the field in advertising, as such companies as General Motors Co., McDonald's Corp. and purveyors of soft drinks took top slots. In the b-to-b arena, online and e-commerce companies increased their expenditures from $213.5 million in the first half of 1999 to $616.5 million in this year's first half. However, that number could drop in the second half of 2000, as advertising spending by Internet start-ups appears to have dropped significantly in recent months.