IBM is in talks to buy Sun Microsystems, sources tell the Wall Street Journal, in a deal that could be completed as early as this week. IBM would likely dole out at least $6.5 billion for Sun, a premium of more than 100% on yesterday’s closing price. Sun has been shopping itself for months, getting shot down by HP, among others. IBM is hoping the move, potentially its biggest ever, would bolster its online business. (More IBM stories.)