Image: Bill Gates and Warren Buffett © Mark Lennihan AP, Carlo Allegri AP

Related topics: Forbes 400, richest Americans, Bill Gates, Warren Buffett, Larry Ellison

It has been a year of reclamation for America's richest. The total net worth of the Forbes 400 is up 8%, to $1.37 trillion, well outgaining the 1% rise in the Standard & Poor's 500 Index ($INX)over the past 12 months. More than half (217) are richer than they were a year ago.

The headline numbers tell only part of the story. About 45% of the 400 failed to add to their fortunes or lost ground. And the record of $1.57 trillion in total net worth, set in 2008, still stands.

The very top of the list gained, with good friends Bill Gates and Warren Buffett up $4 billion and $5 billion, respectively. They are short of their personal highs, though.

No 1: Bill Gates, $54 billion

Source of wealth: Microsoft

Residence: Medina, Wash.

Age: 54

2009 rank: No. 1

In March, Gates lost his title of world's richest person to Mexico's Carlos Slim Helú. But that's because the software king is the most generous person on the planet. To date, he has cut checks totaling $28 billion. Even so, Gates is still America's richest person, topping the Forbes 400 for the 17th straight year.

Most of his donations have passed through the Bill & Melinda Gates Foundation, which now has a $33 billion endowment, including contributions from his buddy and bridge partner Warren Buffett. The foundation has given money to help prevent millions of deaths from AIDS, malaria and tuberculosis; now it's undertaking the eradication of polio. It is also fighting hunger by helping 400,000 farmers in Asia and Africa with rice varieties that resist cold, flooding and drought, and by giving 100,000 farmers on those two continents access to small, inexpensive irrigation systems.

As the foundation's work accelerates, Microsoft (MSFT, news)is stuck in neutral. Gates' stake in the company he co-founded is now worth $16 billion; its stock has been flat over the past year despite the release of a new Windows operating system and heavy investments in online advertising and games. (Microsoft owns MSN Money.)

Gates regularly sells shares in the software giant, pouring proceeds into investment outfit Cascade, which accounts for 70% of his wealth. Other investments include trash collector Republic Services (RSG, news), investment firm Gamco Investors (GBL, news), vehicle seller AutoNation (AN, news)and an inflation-hedging fund.

No. 2: Warren Buffett, $45 billion

Source of wealth: Berkshire Hathaway

Residence: Omaha, Neb.

Age: 80

2009 rank: No. 2

Along with bridge partner Gates, Buffett is coaxing America's richest to pledge half of their fortunes to charity. "You keep making the list; I'll keep milking it," he says.

The Oracle of Omaha plans to give 99% of his wealth to charity, primarily to the Bill & Melinda Gates Foundation, and it all has to be spent 10 years after he's gone. "Too often a vast collection of possessions ends up possessing its owner. The asset I most value, aside from health, is interesting, diverse and long-standing friends."

Buffett's Berkshire Hathaway (BRK.A, news)continues its capital stewardship excellence, beating the S & P 500 Index by 15 percentage points over the past 12 months. His secret to success: emotional stability. "When you come to a conclusion, you have to really not care what other people say," he says.

Buffett faked breathing problems when he was 12 so he could move back to Omaha from Washington, D.C., where his father was a freshman congressman. He had read every book about investing in stocks in the Omaha Public Library by the time he was 12.