Michael Dell will return to the helm at the company he founded, replacing Kevin Rollins, who resigned as CEO effectively immediately Wednesday, as the computer maker continues to struggle in an increasingly competitive market.

Rollins was named CEO in July 2004, though Michael Dell remained as chairman of the company’s board of directors and “deeply involved” with the company’s operations.

Since then, Dell has faced significant hurdles as competitors such as HP and IBM have increased pressure in the low-end of the market where Dell has specialized.

In addition to financial woes, Dell also was the subject of a battery recall and an SEC investigation. In October, the company announced Dell 2.0, a plan to reinvigorate the ailing company.

Organizational changes within Dell have included several executive shifts, including the planned departure of Joe Marengi, senior vice president of the Americas for Dell, who will retire next month. Donald Cary, a Dell director since 1992, took over as vice chairman and CFO in December, replacing James Schneider.

“The Board believes that Michael’s vision and leadership are critical to building Dell’s leadership in the technology industry for the long-term,” Samuel A. Nunn, presiding director of Dell’s Board, said in a statement. “There is no better person in the world to run Dell at this time than the man who created the Direct Model and who has built this company over the last 23 years.”

“Dell has tremendous opportunities ahead of it,” Michael Dell says in the statement. “I am enthusiastic about Dell 2.0, which includes our plan to provide the best customer experience, build a strong global services business and ensure our products deliver the best long-term customer value.”

Dell says it expects its fourth quarter fiscal year 2007 results to be below analyst estimates for both revenue and earnings per share.