Nicholas Brendon, the sardonic Xander Harris who helps the title character ward off werewolves and other creatures of the night on the hit series "Buffy the Vampire Slayer" (The WB, 1997-2001; UPN, 2001- ), turned to acting when an arm injury quashed his professional baseball aspirations. The handsome, dark-haired actor landed his first professional work in a Clearasil TV commercial before appearing in a recurring role on the daytime soap opera "The Young and the Restless" (CBS) and guest-starring on Fox's popular primetime comedy series "Married ... With Children". With roles few and far