He certainly won't have to tighten his belt, but Bill Gates, whose net worth was pegged at $81 billion last year, now has a net worth of $44.86 billion. <P> In a proxy statement released Thursday, Gates was listed as having 731,749,668 shares, or 13.7 percent, of Microsoft. Gates' new net worth is based on Thursday's closing price of $61.31 per share. <P> His wife's 214,460 shares, valued at $13.15 million at Thursday's close, are not included in Gates' stocks because he disclaims beneficial ownership, the proxy says. <P> Steve Ballmer, with 4.5 percent ownership, has 239,626,832 shares. <P>