The Giants yesterday landed a monstrously big free-agent prize that likely will go down as either a huge coup or a major miscalculation with the ink all but dry on a contract for linebacker LaVar Arrington.

The two sides were closing in on an agreement that would allow Arrington to add his name to a linebacker legacy with the Giants and perhaps jump-start a career that not long ago was believed to be destined for greatness.

Thus ends a six-week odyssey and a protracted period of gamesmanship, with the Giants refusing to significantly up their ante and fully prepared to move forward without Arrington if the price wasn’t right.

No terms were immediately available, but the Giants did not come close to matching the seven-year, $54 million package or the $18 million in guaranteed money Julian Peterson, another linebacker represented by the Poston brothers, received from the Seahawks. Arrington was seeking a similar deal.

Instead, the Giants put together a deal that is heavily incentive-laden, allowing Arrington to get paid like a superstar only if he performs like one. That protects the Giants in case Arrington’s right knee is not sound or if his best days are behind him.

Arrington fills a gaping void at weak-side linebacker and adds more star power to a defense that already has Pro Bowl ends in likely Hall of Famer Michael Strahan and rising star Osi Umenyiora as well as middle linebacker Antonio Pierce, a former Redskins teammate and close friend of Arrington who campaigned long and hard for his signing.

This move allows the Giants to expand their horizons in next weekend’s NFL Draft. The Giants own the 25th overall pick and, without Arrington, would have been forced to hone in on an outside linebacker.

A desire to stay in the NFC East (and face the Redskins twice a year) and play in New York made the Giants a frontrunner to land him. The team brought in Arrington for a visit on March 11 but he refused to take a physical, leaving the Giants wary of the health of his right knee, which needed arthroscopic surgery twice in a 20-month period of 2004 and 2005.

The Giants made an offer, but it was not close to the money Arrington was seeking. That was that until Arrington’s camp, with his market drying up, relented and he returned to New York on Thursday to take a physical. That sparked what a team source described as “substantive talks” starting that night and continuing into yesterday.

Outgoing and personable, his status as the most popular player in Washington took a hit when Joe Gibbs returned to coaching and his staff immediately clashed with Arrington, who was considered too much of a freelancer in the defensive system.

LaVar Arrington

Linebacker

Age: 28 in June

Ht. Wt.: 6-3, 255

Three straight Pro Bowls (2001-03)

Played total of 16 games past two seasons (4 in 2004)

Career: 398 tackles, 22.5 sacks