Are you a fan of mushing but don't particularly care for animals? Well, you're in luck this weekend, as the National Human Dogsled Competition highlights the 2007 Lowell Winterfest Celebration. More than 32 sled teams compete for top dog as the six-member squads (a rider, a musher and four sled pullers) race down 200 yards of icy tundra - or what passes for tundra in Lowell. Toss in live music, fireworks, ice skating and a venerable soup bowl competition and you have an offbeat weekend of wintry excitement. Lowell Winterfest starts tonight at 6:30 and continues all day tomorrow in downtown Lowell. For the complete schedule, go to www.lowellwinterfest.org.