The attorney for the Progress Club Inc., the Rockville corporation charged with operating a place for illegal gambling, promised a jury yesterday he will prove that high-stakes poker and gin rummy played at the club are games of skill, not chance, and therefore not illegal under Maryland law.

"You are about to really learn something about legality, illegality and gambling," said Barry Helfand, grabbing a large, transparent plastic bag of red, white and blue poker chips and rattling them dramatically before the Montgomery County Circuit Court jury. "You are going to learn that Maryland law distinguishes between a game of chance and a game of skill."

Comparing the card games to bowling, Helfand challenged Assistant State's Attorney Matt Campbell to produce "the real definition of gambling," which, he said, is "to hazard something on a game of chance."

But Campbell told the jurors, chosen from a jury panel of 81 during a long selection process yesterday, that the case against the Progress Club is clear-cut.

"The law in the state of Maryland is that it is illegal to play games, including poker, gin and pinochle, for money," Campbell told the jury. "It's that simple."

The corporation could be fined up to $1,000 on each of the six illegal gambling charges brought after Rockville police raided the club last June following a 5 1/2-month undercover investigation. Twenty-one club members, mostly elderly, were arrested and charged with illegal gambling, but charges against all but one were dismissed after the men performed community service.

Long-time club manager Michael Richards, is expected to take the stand today as the prosecution's star witness. Richards also was arrested in the late night raid on the club last summer and charged with 12 counts of managing a gaming house. The state granted Richards immunity from prosecution on those charges in exchange for his testimony.