Shares of Apple Computer Inc. (AAPL) rose to an almost four-year high on Thursday ahead of the launch of Hewlett-Packard Co.'s (HPQ) version of the iPod digital music player and Apple's revamped iMac computer.

Apple and HP, the No. 2 computer maker, earlier this year struck an agreement for HP to resell the iPod (search) under the HP brand name, which will boost its exposure to mass consumer electronics markets.

"Tomorrow you've got HP doing their consumer electronics launch and the HP iPod launch, and next week there's the introduction of the new iMac," said Shannon Cross, an analyst at Cross Research.

Although Apple's introduction of the iMac had been delayed due to International Business Machines Corp.'s (IBM) manufacturing problems with the G5 chip, Cross said Apple is well-positioned for growth.

"Even if they have issues with availability of chips in the near-term due to IBM, there's remarkable demand," she said. "Obviously, at some point the chip issue is going to be resolved and you'll be left with a good amount of pent-up demand."

Shares of Apple closed up $1.61, or 4.9 percent, at $34.66 on Nasdaq in active trade.

Investors who believed that the stock might be more volatile chased after Apple options, particularly calls, which give the right to buy stock at a preset price in the future.

At Thursday's close, roughly 74,710 calls and 21,988 puts, which give the right to sell a stock, changed hands across the U.S. options exchanges. That was more than four times typical average volume, according to market research firm Track Data.

So far this year, Apple stock has climbed 62 percent, compared with a 7.5 percent decline in the Nasdaq amid weakness technology shares.

Apple has already sold more than 4 million of the popular iPod digital music players. In addition, the iPod Mini, which since its introduction has been hampered by tight supplies due to very strong demand, is now more freely available after Hitachi Ltd (search) boosted production of the tiny hard disk drives it uses.

Last month, Apple reported its quarterly net income more than tripled, fueled by surging sales of the iPod and as shipments of Macintosh computers rose 14 percent.

The company also said the next-generation iMac would be available in September.

Limited availability of IBM's G5 chip had constrained revenue and profits associated with Apple's Power Mac computers in its most recently reported third quarter.

HP on Friday is launching a wide range of consumer electronics devices, including printers, PCs, handheld PCs, and other items at a press conference in Miami hosted by Chief Executive Carly Fiorina.