You are a hockey purist.

You would run the Boston Marathon twice if you could watch two hockey teams skate up and down the ice.

You would swim the Charles River if you could see two teams play tenacious, penalty-free defense every day for the rest of your life.

You would climb all the stairs to the top of the Prudential Center just to see Harvard Captain Lane MacDonald, this year's ECAC Player of the Year, score on the breakaway time after time.

Tonight at 8 p.m., you will have your wish when top-seeded Harvard (26-2) faces sixth-seeded Vermont (19-12-1) in the semifinals of the ECAC tournament at Boston Garden.

The winner will play tomorrow night in the 8:30 championship game against the victor of the St. Lawrence-Cornell semifinal game. On the line: a league title and an automatic bid to the NCAA playoffs.

But first, the hockey purist's dream.

The Crimson, the nation's numberone team, and the 14th-ranked Catamounts have played twice already this year, with Harvard sweeping the regular-season series, 3-2 in Cambridge and 5-3 in Burlington, Vt.

But Harvard Coach Bill Cleary knows that UVM has played Harvard tough this year. Very tough.

"They have tremendous ability," Cleary said. "They have some guys who could put the puck in the net. We're going to have to play really well."

And Vermont Coach Mike Gilligan knows that to beat Harvard, the Catamounts must stick to its skating game. One mistake and the puck will probably find the net.

"It's going to take discipline," Gilligan said. "We have to play Harvard as evenly as we can, especially on five-on-five. If we commit too many mistakes, you give them too much ice, and they'll use their speed and skating skill to capitalize."

Gilligan's words must be comforting to Cleary's ears, which had to constantly listen to the referees' whistles during last weekend's ECAC quarterfinal series against RPI at Bright Center.

Last Saturday, RPI's rock'em-sock'em strategy almost worked. The Engineers had a 3-1 lead with less than 12 minutes left in the third period.

Harvard was down. But with the help of a boisterous home crowd, the Crimson wasn't out, scoring four goals in the last 10 minutes of the game to capture a 5-4 victory.

"The fans helped us win our game," Cleary said. "I know how much the hockey team appreciated their efforts, and so did I."

The Catamounts, however, will bring their own crowd to the Garden, as a gold-and-green Burlington invasion will stake a claim to its section at the Garden.

"We're going to get a big charge out of seeing the fans," Gilligan said.

The crowds both Crimson and Catamount, will try to spark the offense on the ice, although the forwards on both teams won't need that much to get charged up.

First Team All-ECAC selection Kyle McDonough, Vermont's "Big Mac Attack," leads the Catamounts in scoring with 55 points (27 goals, 28 assists).

But Harvard has its own "Big Mac Attack" in Player of the Year MacDonald (26-27--53), another First-Team All-ECAC selection and the all-time leading scorer in ECAC Tournament history.

Both sharpshooters are accompanied by a formidable supporting cast.

For the Catamounts, ECAC Honorable Mention Ian Boyce (15-16--41) will anchor the Vermont offense, along with Jim Larkin (16-18--34) and Jim Walsh (13-19--32).

For the Crimson, Peter Ciavaglia (10-41--51), C.J. Young (30-19--49) and Allen Bourbeau (11-37--48)--all Second-Team All-ECAC selections--are three reasons why Harvard has averaged 5.9 goals per game.

At net, Vermont will look to Mike Millham (.865 save percentage, 3.32 goals-against average) to guard the pipes. Harvard's Allain Roy (.914, 2.50), a member of the All-Rookie team, will start for the Crimson.

"We're going to give Harvard a run for the money," Gilligan said.

No hockey purist is complaining.