Lowe's Cos., the nation's second biggest home improvement chain, said Monday that its first-quarter profit fell 22 percent, but exceeded Wall Street expectations.  Profit dropped to $476 million, or 32 cents a share, from $607 million, or 41 cents, a year earlier. Sales in the three months ended May 1 were $11.8 billion, the company said today in a statement. Analysts had projected profit of 26 cents on sales of $11.6 billion, the average of estimates compiled by Bloomberg.