Piper Jaffray expects Apple Computer to gain share in the personal computer market over the next two to three years. Piper Jaffray cited the iPod halo effect, "continuous innovation leading to highly functional products at realistic price points," and security and performance issues for PCs based on Microsoft Windows. The research firm said, "It is important for investors to keep in mind that minimal upside to Mac market share estimates could have a significant impact on Apple's overall results." Piper Jaffray, which maintained an "outperform" rating on Apple, said that assuming "immaterial" market-share gain over the next eight quarters,...