Starting Saturday March 8, the 2003 edition of the Chi-Town Challenge will begin with an additional on-site contest this year. For the on-line challenge, fans can sign up through www.sportsmanspark.com or www.hawthorneracecourse.com before noon on Saturday. To continue in the contest, fans must pick a single horse each day that they believe will finish in the top three in its race. If the horse hits the board, the contestant will advance to the next day. This will continue until there is only one person left standing. The winner will receive a $5,000 top prize. In addition to the on-line contest, a new on-site contest will take place as well. The rules stay the same, but contestants must place their pick at Hawthorne every day. Top prize in the on-site contest is 125,000 Club Hawthorne points, which can be used towards any prize that Club Hawthorne offers...The Kentucky Horse Park in Lexington will operate during its spring hours beginning March 15. The park is open 9 a.m. to 5 p.m. through Oct. 31. Starting April 26 the park will offer "All the Queen's Horses." For more information on the park or its exhibits, visit www.kyhorsepark.com...Reserved seating is now on sale for Lone Star Park at Grand Prairie's upcoming season (April 3--July 13). The weeknight post time is 6:35 p.m., while racing begins at 1:35 p.m. on weekends and holidays. For more information visit www.lonestarpark.com...Patrick Mullins has been elected president of the North American Riding for the Handicapped Association. He has been a board member of the organization since 2000. Mullins is director of agency development at Markel Insurance Company in Glen Allen, Va....Maker's Mark will sponsor Turfway Park's VIP tent on Lane's End Stakes Day, March 22. The distillery will have a special station in the tent with red wax for dipping glasses, and will offer free drinks to guests in that area. Tickets for the tent are $150 apiece. For more information visit http://www.turfway.com/flypage/portal.html...Laura J. Koester has been named Practice Leader of the Private Client Services Bloodstock Division of Marsh Inc. in Lexington. Marsh is a risk and insurance services firm that is an operating unit of Marsh & McLennan Companies.