It didn’t take long for the Nets to achieve their top off-season priority.

Mere hours into the league’s free agency period, the Nets and star guard Vince Carter agreed on a four-year, $61.8 million deal, according to the Newark Star-Ledger, that would keep the high-flying scoring machine at the Swamp. The Nets would hold an option for a fifth year.

The deal can’t be signed until July 11 when the league determines its salary cap figure for 2007-08, but that number should have no bearing on Carter’s contract. Carter had opted out of the final year of his contract a day earlier, one that was slated to pay him $16 million. He’ll now make roughly that amount for four years instead of one.

The immediate question is whether the Nets overpaid. Carter has been an All-Star caliber performer since coming to New Jersey, but he’s also 30 years old. As dependent as he is on his freakish athleticism, one wonders how well that will translate as he gets into his 30s and Father Timestarts robbing him of those explosive hops.

Additionally, the Nets arelooking at dancing with the luxury tax line for the next few years thanks to the contracts of Carter, Richard Jefferson, Jason Kidd and, if extended, Nenad Krstic. That could limit their ability to add enough talent around the “Big Three” to return to the Eastern Conference’s elite.

Nonetheless, this is a far better outcome than seeing Carter leave without compensation. The Nets chances of contending in the East, remote though they may seem now, would be positively nonexistent without Half-Man, Half-Amazing in the lineup.

Moreover, the Nets limited some of their risk by keeping the deal to four years. Carter would be 34 at that time, by which point it’s unlikely that he’ll keep making annual All-Star appearances. But one must presume that he’s likely to stay at close to that level at least for this year and next, which takes up half the length of the contract.

Adding fuel to that argument is that Carter has shown little signs of slippage in recent seasons. Using my Player Efficiency Rating (PER, a per-minute rating of a player’s statistical effectiveness), Carter is basically the same as he was five years ago — his marks the past five seasons have been 22.0, 20.0, 22.9, 21.7, and 21.9.

Plus, players who shoot as well as Carter does usually have an easier time in their 30s than those who have to get all their points around the basket — especially ones like Carter that have had no serious injuries.

All told then, Nets fans have to view this as a positive. The last year or so might get a little ugly, with Carter eating up a massive chunk of the salary cap while likely in precipitous decline. But at that point the contracts of Jefferson and Carter would expire simultaneously, allowing the Nets to go in a new direction in 2011 when they’re firmly ensconced in Brooklyn (at least, if there aren’t anymore lawsuits).

With Job 1 out of the way, the Nets don’t seem to be done dealing. Rumors had them preparing to lure Washington’s Andray Blatche with a multiyear deal. The 6-11 forward won’t turn 21 until a month from now, but has shown promise in his two seasons with the Wizards. However, he’s a restricted free agent, so the Wizards would have the right to match any deal.

And there’s another, bigger fish the Nets also are trying to hook. Conversations with Indiana about power forward Jermaine O’Neal have centered on a package of Jefferson, Krstic and Jason Collins, and while talks have cooled for now they easily could heat up again over the next three months.

Though he’d be expensive, O’Neal would provide the post scorer this team has been longing to have for ages. Additionally, he’s a monster defensive presence who would solve the team’s need for a shot-blocker. However, the cost of three starters seems prohibitive from the Nets’ standpoint and they’d probably need a sweetener to pull the trigger.

One player who is unlikely to return to the Nets is big man Mikki Moore. His outstanding 2006–07 season may have priced him out of New Jersey’s range, and truth be told it was probably a fluke year anyway.

Between the expected pursuit of Blatche and the drafting of big man Sean Williams on Thursday, it’s a loud statement that Moore probably isn’t coming back. Additionally, a deal with Blatche would cut a big chunk out of the Nets’ midlevel exception — the same pot that the money to keep Moore would have to come from.

As for the Knicks, the opening day of free agency wasn’t as kind — one of their prime free-agent targets doesn’t seem to be returning the love. Sonics forward Rashard Lewis met with his current team on Sunday, then immediately headed off to Orlando to be wined and dined by the Magic. That club appears to be his first choice should he leave, and unlike the Knicks the Magic can cut a deal without needing to do a signand-trade.

Aside from the Carter deal, there was little other earth-shattering news from free agency’s first several hours, as teams awaited info on the other major free agents — Lewis, Detroit guard Chauncey Billups, Charlotte forward Gerald Wallace, and Milwaukee guard Mo Williams — before moving down their list.

However, a couple of teams decided not to wait on the bigger dominoes falling before pulling the trigger on secondary deals. The Lakers retained savvy forward Luke Walton with a six-year, $30 million deal, ending speculation that he’d be included in a sign-and-trade deal to bring back another star for the Lakers.

More surprisingly, Toronto gave up on its pursuit of Orlando forward Grant Hill in order to sign Miami sharpshooter Jason Kapono to a four-year deal for the midlevel exception, a deal which appears to significantly overvalue the 26-year-old forward based on one good year.

Nonetheless, it’s another sign that the Nets’ neighborhood is going to be tougher this year. Boston and the Knicks already pulled in a pair of high-scoring stars from the Western Conference, and now the division champion Raptors are adding to their haul as well.

All of which makes Sunday’s move by the Nets even more imperative. For all his faults — many of which were abundantly displayed during the playoff loss to Cleveland — Carter is the best scorer on what is otherwise a fairly horrendous offensive team.

Keeping him keeps hope alive that the Nets somehow can return to their former glory. For the rest of the summer, at least, that hope remains alive.

jhollinger@nysun.com