Triangle landlords have almost won the battle against empty offices -- a war they began to wage after tech companies bailed out in the early 2000s. But one final firefight could be emerging in and around Research Triangle Park.

By April, computer maker Lenovo will have moved out of at least 350,000 square feet of RTP-area offices and into its new Morrisville headquarters.

Most of the space left behind will be in Durham's Pinnacle Park, where three landlords will compete to fill four buildings, totaling 280,000 square feet, that stare at each other across Silicon Drive.

Meanwhile, Lenovo plans to move out of 130,000 square feet at Park Center in RTP, and IBM was to move out of 131,000 square feet at 9 Davis Drive last month -- two more landlords, 261,000 more square feet of emptiness.

A few years ago, it would have been the recipe for a bloodbath.

Struggling companies shrunk or shuttered, causing the RTP submarket's office vacancy rate to climb to 25 percent in 2004 from below 5 percent in 2000, according to data from Highwoods Properties. Landlords battled over the few tenants who wanted space. They paid tenants' moving expenses, did complementary interior construction and slashed rents.

Older offices such as those at Pinnacle, Park Center and on Davis Drive were worse off, as many tenants upgraded to class-A space when the dealing was good.

At the end of 2004, 59.3 percent of the class-B offices in the RTP submarket were empty. Although the rate dropped to 20.6 percent at the end of 2006, the recovery has apparently come at a cost.

Class-B office rents in the submarket have dipped 4 percent to $15.58 per square foot since 2004, while jumping 5 percent to $16.10 across the region, according to Raleigh brokerage Grubb & Ellis/Thomas Linderman Graham.

Indeed, the fight to fill 541,000 square feet of existing offices in RTP doesn't seem easy today -- especially as another 1.4 million square feet are being built across the region, including 388,000 in the RTP area.

But landlords and investors aren't as worried about the skirmish. Here's why:

* Across the region, there's less empty space to compete against than a few years ago. The Triangle's office vacancy rate dropped to 13 percent at the end of 2006 from 14.1 percent a year earlier. In the RTP submarket, the vacancy rate dropped to 14.5 percent from 18.7 percent during the same period, according to Highwoods.

* Leasing is up. The Triangle's net absorption, the total space leased minus the total vacated, was 716,387 square feet in the fourth quarter, even as 515,024 square feet were built. That's the most absorption in any quarter since 2004, and more than twice the quarterly average since 2004. Half the absorption was in the RTP area, where 303,032 square feet were built in the fourth quarter.

"If you're going to get a lot of space back, you're going to want it in the most vibrant market, and that's RTP," said Lee Clyburn, a Grubb & Ellis/Thomas Linderman Graham broker who represents landlords of three Pinnacle buildings. "... All these buildings will compete aggressively."

* Pinnacle, Park Center and the Davis Drive offices will have a price advantage over new buildings. There are few big chunks of offices available in the Triangle, let alone inexpensive chunks. Companies that need a lot of space in one place usually have to turn to new buildings, where some rents are edging north of $25 per square foot annually. Class-A rents across the Triangle rose 2.4 percent to $19.20 per square foot in 2006. Asking rents at Pinnacle and Park Center range from $14 to $18 per square foot. The Davis Drive space could go for $9 per square foot.

There's also a chance that owners at older RTP space won't compete with each other. Indeed, they might cooperate if a company moves to the Triangle in search of lots of space. "That would be the ultimate outcome: A large user says, 'I need a quarter of a million square feet.' " said Mark Prevost, a CB Richard Ellis broker who represents a Pinnacle landlord. " 'Well, have we got a deal for you. We just happen to have a quarter-million square feet with 10 percent growth in four offices at Pinnacle.' "

Investors are taking advantage of the upcoming glut. Last month, a partnership led by Professors Capital of Fairfax, Va., paid $2.66 million, or about $44 per square foot, for the 60,000-square-foot Pinnacle Park building at 4408 Silicon Drive. And First Colony Property paid $3.26 million, or about $41 per square foot, for the 80,000-square-foot Pinnacle Park building at 4407 Silicon Drive, according to Durham records. The bargain price per square foot -- less than half the average -- reflects the vacancy.

"Purchasing a soon-to-be-vacant building in RTP would be unheard of even 12 months ago," said Ben Kilgore, a CB Richard Ellis broker who represented the seller of 4407 Silicon. It "indicates that the overall economy, capital markets and investors view the Triangle as a growth market."