http://news.yahoo.com/s/nm/financial_buffett_taxes_dc NEW YORK (Reuters) - Billionaire Warren Buffett on Monday called for U.S. lawmakers to retain the estate tax, after announcing plans to leave more than $37 billion of his own fortune to charity, not his children. Buffett spoke after agreeing to sign over roughly $30.7 billion of his $44 billion fortune to the Bill & Melinda Gates Foundation, run by the Microsoft Corp. chairman and his wife, and another $6.4 billion to foundations on behalf of his late wife Susan and his children. "I would hate to see the estate tax gutted," Buffett said at a Manhattan news conference with the Gateses about his donation. "It's a very equitable tax," Buffett said. "It's in keeping with the idea of equality of opportunity in this country, not giving incredible head starts to certain people who were very selective about the womb from which they emerged."