The Celtics’ Kevin Garnett argues for a foul call during the first quarter of last night’s game against the Pistons at Auburn Hills, Mich.

AP / Tony Dejak

AUBURN HILLS, Mich. — For any Boston Celtic fan who grew up with Bill Russell, Dave Cowens or Larry Bird leading their team to championship glory, playoff basketball ruled every spring in New England.

Russell and Bob Cousy rolled to titles nearly every April and as the NBA calendar kept expanding, the Cowens and Bird-led Celtics of the 1970s and `80s were a fixture on the New England sports scene virtually every Memorial Day and into the warm, summer days of June.

Over the last 20 years, Celtic fans learned to cherish the glory years. No longer could they take winning for granted. That fact is never more evident than it is today.

For the longest time, the Celtics all but owned the NBA playoffs. The memories of Cousy, Bill Sharman, John Havlicek, Dennis Johnson and so many other legends created the greatest franchise in the sport. That dynamic ended when Bird retired in 1992. Ever since, the Celtics’ playoff runs have been brief, if they occurred at all. Over the next 16 seasons, the Celtics won at least one playoff series in only two seasons. Only the 2002 team went as far as the Eastern Conference finals.

Then came the volcanic, dynamic summer of 2007. With two monster trades, Danny Ainge rehabbed the franchise by adding Kevin Garnett and Ray Allen to the team that already had Paul Pierce. In one season, the Celtics went from bottom-feeder to a team with one, clearly stated goal: a return to championship timber.

So far, Allen, Garnett and Pierce have delivered. The so-called Big Three rejuvenated the franchise, rolling to a NBA-best 66 wins in the regular season. The Celtics are playing on Memorial Day again and dreams of a spot in The Finals is once again within reach.

The question is how long can this group keep it going? If Celtics’ history has taught us anything, it’s that you need stars to win big and Allen, Garnett and Pierce can’t play at the star level forever. In fact, this could be a very short window.

Here are the pertinent facts: All three of the team’s stars are over 30 years old. They are closer to the end than the beginning of their careers. Allen will turn 33 in July. Garnett just celebrated his 32nd birthday. Pierce will be 31 years old at the start of next season. They are currently in the prime of their careers but in an NBA dominated by younger and younger talent, players dominating beyond their 35th birthday are few and far between.

The Celtics are certainly set for the next two seasons. That’s when Allen’s contract, which will pay him $18.7 million in 2010, expires. Pierce’s deal expires after 2011. He’ll pocket $21.5 mill that season. Garnett is under contract until 2012. He’s the highest paid player in the NBA right now ($23.7 million) and a restructured deal has him making $21.2 when he’s 36.

None of the players would bite when asked about the team’s window of opportunity. They all want to win their first championship now, not next year or the year after.

“It’s hard to think about it from a perspective of an end,” said Allen. “You just want to take care of yourself and try to milk the situation as long as possible.”

As the Celtics proved this season, they have more than enough firepower to roll through the regular season and win the Atlantic Division for the next few years. Garnett clearly is still an elite player and he seems to have four big years left. Pierce will always be a big scorer and it’s hard to believe he won’t be able to score 20 points a game for the next three years.

Allen is another matter. His struggles in the playoffs show that his scoring skills may be sliding. While he should be good to go for the two years left on his deal, he’ll likely be done after that.

Right now the Celtics lack any young player outside of Rajon Rondo who could remotely be termed a building block for the future. It’ll be up to Ainge to find more players with promise as a way to transition from the veteran trio to a new wave of stars.

Getting this current group with its short window of opportunity past the Detroit Pistons will take the fight of their basketball lives. But winning now and getting a shot at the Lakers or Spurs next month is an opportunity that cannot slip away and one that Celtics’ fans will surely cherish.

kmcnamar@projo.com