Microsoft And Google: Partners Or Rivals?
Google, highflying Silicon Valley Web search company, recently began holding meetings with bankers in preparation for its highly anticipated initial public offering as it still engaged in meetings exploring partnership or even merger with Microsoft; Microsoft, desperate to capture part of popular and ad-generating search business, approached Google within last two months to discuss options, including possibility of takeover; overture demonstrates enormous importance that Google represents as both competitive threat to Microsoft and as Silicon Valley's latest hope for new financial boom; photos (M)