Decisions in the past two days have suddenly given Washington Bullets general manager John Nash a $900,000 surplus in the team's salary cap with which to ponder a future acquisition.

Nash first gained $130,000 by waiving reserve center Ralph Sampson, who has chosen to play the rest of the season in the Spanish Basketball League.

Most of the rest came yesterday, when the National Basketball Association acted favorably on Nash's appeal to subtract half of suspended forward John Williams' $1.2 million salary from the $12.5 million team limit.

For the second straight year, an overweight Williams was placed on medical suspension, and his salary was withheld. He appealed last year's $426,000 reduction in pay, and an arbitration ruling is due later this month. Williams' agent, Fred Slaughter, has requested another arbitration hearing over this season's suspension.

In any case, the NBA will allow the Bullets to carry over this surplus into next season, if so desired. A precedent was set earlier this season when the league let the Los Angeles Lakers subtract Magic Johnson's $3 million-plus salary after the superstar contracted the virus that causes AIDS. The Lakers then made an unsuccessful bid to lure point guard Sherman Douglas from Miami, with the Heat matching their offer sheet.

With Sampson gone, Nash could pursue another big man to bolster Wes Unseld's injury-riddled frontcourt. He will be scanning the waiver wire today, when teams must cut players or be obligated to pay them a full year's salary.

The Bullets now have only 11 active players, but forward Tom Hammonds, sidelined with a groin injury, is expected to return shortly. Forwards Bernard King and Mark Alarie are recovering from knee surgery and not expected back before February, if then.

The most vulnerable Bullet, if Nash decides to make a move, is Andre Turner, who has been unimpressive in his role as an understudy to point guard Michael Adams.