Worldwide sales of personal computers in the second quarter of 1997 grew 15% over the year-ago period, according to research firm International Data Corp. The 15% year-over-year growth in unit shipments was equal to that recorded in the first quarter of the year. US sales saw a higher-than-average growth rate of 19%. IDC says market demand was bolstered by the introduction of Pentium II desktops and heavy corporate investment in system upgrades. Compaq Computer Corp retained its top market share position, both in the US and worldwide. Hewlett-Packard Co jumped to the number three position worldwide with 48% year-over-year growth and IBM Corp retained the number two spot worldwide. Dell’s 52% growth placed it fourth in the world and third in the US. Packard Bell NEC Inc rounded out the top five vendors, showing growth (5%) for the first time since the merger of Packard Bell, NEC, and Zenith Data Systems last year.