HORSEPOWER

The Washington International Horse Show canters on at the Capital Centre Friday to Sunday. Competition includes dressage, terrier races and puissance, better known as The Wall -- a high jump for riders and horses. Tickets are $5 to $30; call 432-0200 for details. And see the story on page 58.

LEFT BY THE BAYSIDE

Be true to your bay at Chesapeake Appreciation Days 9 to 5 Saturday and Sunday at Sandy Point State Park. Both days, there'll be air shows, canine demonstrations by (what else) Chesapeake Bay Retrievers, bathtub races, jousting, juggling, storytelling, clogging demonstrations, sailboat and skipjack races and seafood for sale. It's $4 per person (free for under 12) at the park, just this side of the Bay Bridge. 301/647-4747.

PASTIMES

Get a look at just how glamorous train travel used to be at the 10th annual Gaithersburg Railroad and Transportation Show 10 to 5 Sunday at the Montgomery County Fairgrounds. More than 400 dealers will have china, silver, lanterns, signs, locks, timetables and other memorabilia from trains and steamships, airplanes and buses. Admission to the fairgrounds (on Rte. 355) is $3.50, free if you're under 12. Call 536-2954.

The National Cathedral antique show features quilts, linens, furniture, Victorian clothes and 16th- to 19th-century prints, among other dainty items for sale, 11 to 6 Saturday and noon to 5 Sunday in the auditorium of Hearst Hall at Wisconsin and Woodley NW. Free. Call 244-0859 or 363-7086.

REST OF THE BEST

This is the last weekend to see the National Symphony's Decorator Showhouse at Belle Terre, 9401 River Rd. in Potomac. It'll be open 10 to 3 Friday, 10 to 4 Saturday and noon to 5 Sunday. Tickets are $10. (No one under 8 admitted.) 299-4422 . . . the Capitol City Chapter of the Beer Can Collectors of America is having a trade show 10 to 5 Sunday at the Anacostia River Park, Riverdale and Tanglewood streets in Riverdale. Free. 698-9591 . . . There's a Swedish Bazaar at the Church of the Little Flower, 5601 Massachusetts Ave. in Bethesda 11 to 3 Saturday. Call 897-9321 . . . the World Peace Foundation celebrates World Peace Day 11 to 5 Sunday at the Reflecting Pool next to the Lincoln Memorial. After all the entertainment, which includes storytelling, folk music and dance, children can make, light and float lanterns on the water. Free. 363-8586.

LLAMARAMA

Looking for something unusual for the weekend? How about the first East Coast Llama Jamboree in Culpeper? To show off the ever-popular cousin of the camel, the jamboree features lots of llama sports, including obstacle courses, cart-driving competitions and flapjack races (in which the llama runs after the owner while the owner flips pancakes, see). For $1,000 to $80,000, you could even make like Michael Jackson and buy a llama. It's 9 to 5 Sunday at Commonwealth Park; $7 at the gate, $5 for ages 12 to 20, $3 under 12 and free for under 3. The park is on U.S. 522, four miles south of Culpeper. 703/832-3076.

HO HO HO?

If you have an event to be included in Weekend's annual roundup of Christmas-related activities (concerts, fairs, celebrations, etc.,) to be published December 4, send information to Ho-Ho-Hos, Weekend, Washington Post, 1150 15th St. NW, DC 20071. We must receive announcements in writing by November 27.

STEEP STREET

As the weather gets cooler, a skier's thoughts turn to the slopes. If that's where yours are, check out the second annual Ski Carnival at the Patriot Center 6 to 10 Friday, 11 to 10 Saturday and 11 to 6 Sunday. There'll be more than a hundred booths with the latest in equipment, supplies, clothing, plus free screenings of ski/film guru Warren Miller's 87-minute film "White Winter Heat," that'll take you down some of the most beautiful and dangerous slopes in the world. Admission is $7.50 for adults, $5 for kids 6 to 12 and free for the rest. 432-0200.

POE COMES ALIVE IN BALTIMORE

Get scared to death at the Edgar Allan Poe House at 203 North Amity Street in Baltimore, where they'll present dramatic presentations of two of Poe's most famous tales of terror this weekend. "The Tell-Tale Heart" and "The Black Cat" will performed by actor Tony Tsendias at 12:15, 1:30, 2:45 and 4 Saturday and Sunday. It's $2; first come, first served. Call 301/396-7932. For many more grownup Halloween events, see page 53. (For family activities and events, see page 56.)

AU PIED

Flock together for FLOC, For the Love of Children, and its 20K C&O Canal walkathon that begins with registration at 9 Saturday at Carderock Recreational Park. Walkers can take a break for Halloween games (like face-painting and a bean bag toss) and eat free pizza after the walk. For the tired, there'll also be a Weary Walker Wagon. It's free, but pledges are required. Proceeds also benefit Project Concern International. For details, call 333-8624.

ADD-ENDUM

Add Arts refuses to be rained out. To make up for the events postponed on Labor Day, the outdoor arts festival will take to the streets on a smaller scale between noon and 5 Saturday. Expect all the good things that were planned last time, including the Artist's Invitational Graffiti Wall, an open-mike marathon at d.c. space and performances by Ajax Moving Company and reggae by Black Sheep. It's in conjunction with the opening of Stables Arts Center, which Mayor Barry will formally open at 1. Free. 783-0360.

STUFFIN'

Kids and parents can head over to the Old Post Office Pavilion and get hands-on lessons on scarecrow making from Mark Baron, "the world's only living scarecrow," between 2 and 4 Saturday. It's free at 1100 Pennsylvania NW. 289-4224.