Hot dogs, baked beans, humidity and 90 degrees . . who needs it ? Sitting in air conditioning, sipping Mountain Dew, eating Fritos, playing online computer games for a trip to the World Series or the Stanley Cup . . .  Priceless ! The real way to enjoy the summer is set in front of your computer and play games for real prizes at www.mastercard.com. MasterCard kicked-off its summer Internet promotion last week. The promotion involves a trio of online sports games. Web heads can play baseball, golf, and hockey for some really decent prizes. The three '"Priceless Summer Escape Grand Prizes" include the "Tee-Off Sweepstakes" a 3-day/2-night trip for three to the Colonial Country Club in Fort Worth, Texas for a round of golf with PGA Tour star Justin Leonard; "Homerun Sweepstakes"  a 3-day/2-night trip for four to the 2000 Major League Baseball World Series, where the lucky winner will watch a game with Hank Aaron; "Rapid Shot Sweepstakes" a 3-day/2-night trip for 4 to Game #4 of the 2001 National Hockey League Stanley Cup Finals, where the lucky winner will watch the game with Bobby Orr. To play MasterCard's virtual games visit www.mastercard.com. .