Netscape Communications Corp. said its Navigator Internet browser software will be packaged with U.S. Robotics modems, giving a boost to Netscape in its browser war with Microsoft Corp. Navigator will be distributed as part of the software with U.S. Robotics' Courier and Sportster desktop modems. Netscape is aiming to distribute 100 million copies of Navigator over the next year through partners, including Internet service providers and U.S. Robotics, a division of 3Com Corp. Wide familiarity with Navigator helps Netscape sell its higher-end Internet software packages, especially to large companies. Mountain View-based Netscape is fighting much larger Microsoft, which has been gaining market share for its Internet Explorer browser software. Santa Clara-based 3Com is the world leader in modems, with a U.S. market share of more than 40%. In Nasdaq trading, Netscape shares rose 6 cents to close at $38.94; 3Com shares fell $2.06 to close at $47.38.