Main market news: Before the bell 7-30-07: Investors unsure before today's open

The Utility Belt examines the secret of Apple Inc.'s (NASDAQ: AAPL) iPhone's success. Not surprising, it's the software.

Barron's Online's Dimitra Defotis isn't so positive on Amazon.com Inc. (NASDAQ: AMZN) as many of its investors are: the stock trades at high multiples that rely too much on margin expansion. AMZN shares are down over 1% in premarket trading.

Caterpillar Inc.'s (NYSE: CAT) rival Komatsu Ltd. lifted its full-year outlook above expectations as strong demand bumped up quarterly profit 65%.

Ford Motor Co. (NYSE: F) is up over 2% in premarket trading (8:00 a.m.), possible due to an upgrade on Friday of Merrill Lynch from Sell to Neutral following a good second-quarter report according to our friends at Flyonthewall.com. There is interest from two companies in Ford's Jaguar and Land rover units, which undoubtedly contributes to positive sentiment on the stock. General Motors (NYSE: GM) is also up in premarket trading ahead of its reported earnings tomorrow.

Lehman Brothers upgraded MGM Mirage (NYSE: MGM) to Overweight from Equal-Weight and raised its price target to $82 from $72. Lehman believes "the stock has at least 14% upside potential and doesn't need the presence of M&A or private equity investment to get there." MGM shares are up about 2.2% in premarket trading (7:50 a.m.).

JMP Securities analyst Samuel Wilson upgraded Motorola Inc. (NYSE: MOT) to Market Perform from Market Underperform, as shares are near his $17 price target. While the analyst still sees the company struggling, he thinks most of it is priced in. MOT shares are up 0.8% in premarket trading.

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