NEW YORK (CNN/Money) - Viacom Chairman Sumner Redstone said Tuesday that plans to split the media conglomerate into two separate, publicly traded companies are moving forward and that he is "personally committed" to seeing it happen.

Redstone, speaking to analysts after Viacom reported higher first-quarter sales and earnings that topped Wall Street forecasts, said he expects a vote by the company's board of directors on a breakup plan in the coming months. If approved, he said, a split could come by the first quarter of 2006.

Viacom (up $0.71 to $34.67, Research) stock rallied on Redstone's comments and the earnings numbers, rising about 2 percent in morning New York Stock Exchange trading.

When Viacom first announced a month ago that it was eyeing a breakup, it committed to no specific time frame. The company is making the move after years of growth through acquisitions have failed to boost its stock price.

The March 16 news ignited a brief rally in Viacom stock and fueled speculation on Wall Street that other media giants, among them Time Warner (Research), might consider a similar breakup.

But Viacom stock has fallen back to pre-announcement levels and no other major media company has signaled any plan to follow Viacom's lead. CNN/Money is a unit of Time Warner.

Redstone's comments Tuesday were more definitive than his statements a month ago.

"It's the right strategic plan for our future," he said, adding it's a "complicated process that takes time to fully analyze. The one thing involved that is not complicated is our motivation (and) I want all of you to know that I am personally committed to achieving the separation."

And he predicted that Viacom competitors will eventually follow his lead as competition in the entertainment industry mounts with the growing use of online and wireless devices.

The basic idea is to form two new companies, one that appeals to investors looking for predictable returns with low-risk and the other a more aggressive, high-risk company.

The more staid company would include Viacom's CBS and UPN broadcast networks, its Infinity Broadcasting radio and outdoor advertising business, and its Simon & Schuster book publishing division. The company would be led by current Viacom co-president Leslie Moonves.

The high-growth company would consist of MTV and other cable networks, the Paramount Pictures movie studio and other assets. Viacom co-president Tom Freston would head up the second operation.

In commenting on the huge promise of wireless entertainment, Redstone said it is "vital" for any company chasing those consumer dollars to be "nimble and innovative." He suggested that the Freston-led company would have that flexibility.

In its earnings, Viacom said strong cable network advertising helped drive total sales up 5 percent to $5.6 billion. Earnings from continuing operations of $585 million, or 36 a share, topped forecasts of 31 cents.

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