Elsie Cunningham's landlord presented her with a difficult choice: buy her Arlington apartment or pack up and move.

Cunningham, 62, had been renting the two-bedroom unit for $1,300 a month. Earlier this year, the landlord at the Brittany complex said she could buy it for $421,000, which would require a mortgage far beyond her means.

"We had a lot of elderly and disabled friends . . . who had planned on dying at the Brittany," said Cunningham, a retired federal worker who lived there for 18 years. "The shock of having to move very quickly because they could not afford to purchase their homes or did not want to purchase was devastating."

Landlords seeking to exploit skyrocketing real estate prices are converting apartments into condominiums at a blistering pace, a trend that is providing new buying opportunities for some of the region's middle-class residents but is also pushing thousands of less-affluent residents out of their homes.

Five thousand area apartments become condos in 2003, and a whopping 14,500 in 2004, according to Delta Associates, a real estate consulting firm. The number of conversions this year is expected to far surpass last year's total, housing officials say.

When apartments are converted into condos, renters are offered the first chance to purchase a unit, usually at a discount. But only a small portion -- usually about 10 percent -- do so, housing analysts say.

The rest have to scramble to find other places to live. And they do not have much legal recourse, especially in Virginia, where the laws generally favor the rights of property owners over tenants.

Housing officials, alarmed over the dwindling supply of reasonably priced rentals, say the trend will exacerbate the region's affordable housing crisis.

Melodie Baron, a division chief in the office of housing in Alexandria, said: "The city is very concerned about it. This is an awful lot of affordable rental housing to be losing." Nearly 2,400 apartments, or 10 percent of the city's rentals, became condos in less than two years.

Many jurisdictions are proposing programs to help displaced renters, often at taxpayer expense. Some provide no-interest loans and mortgages to help first-time home buyers. Montgomery County imposed a 4 percent tax on condo conversions to help cover an affordable housing fund. Last month, Alexandria approved providing $30,000 no-interest loans to help renters of converted apartments buy their units. The income limit for a family of three to qualify for the loan is $89,300.

Fairfax County, meanwhile, has earmarked a penny of the real estate tax rate for an affordable housing fund that will provide incentives meant to keep some affordable rentals from becoming condos.

Housing officials expressed another worry. At a time when housing analysts are fretting about a possible real estate bubble, the sudden flood of converted condos may put downward pressure on prices, some warned.

"It seems like almost every week a new property is trying to convert to condos," said Elizabeth Davison, director of Montgomery County's Department of Housing and Community Affairs. "It's going to get overbuilt. Property owners are rushing to get their buildings out on the market before the bubble bursts. . . . They are frantic to convert."

The conversion of the Brittany, a 408-unit high-rise on South Four Mile Run Drive, forced scores of residents to find another place to live.

Cunningham, who moved out in April, decided to buy a cheaper and smaller two-bedroom condo in Alexandria. But her monthly expenses went from $1,300 to $2,000 a month.

She said she considered herself fortunate to be able to afford anything. Many of her friends from the Brittany face less attractive options. Some are moving into senior housing or spare bedrooms in relatives' homes, she said.

The rash of conversions, however, is encouraging some to get into the home-buying market.

A few blocks from the Brittany, in a sprawling garden-style complex known as the Shirlington Overlook, David Orgel, 52, decided to buy his one-bedroom apartment after the price was set at $256,500, about $33,500 below the sales price offered to the general public. Under an arrangement between the developer, KSI Services, and the Virginia Housing Development Authority, Orgel qualified for a low-interest loan and will be exempt from a down payment requirement.

KSI President Richard Hausler explained that the complex needs $30 million in renovations and that condos are priced high enough now to cover the cost and then some. The new units will have stainless steel appliances, granite countertops and other luxury amenities.

"It's creating new homeownership opportunities," Hausler said of the conversion. "Two years ago, you couldn't have done that."

Yet only 51 tenants out of 520 units signed up to buy, despite the benefits of KSI's offer. Most Overlook residents are immigrants with low incomes, and few could afford even the lower price offered to tenants, according to housing advocates in Arlington. Many apartments are shared by several families to save on rent.

"In three years or so, this place will be all yuppie, and that really changes the character of Arlington," said Orgel, who owns a printing business. "It's great for property values. There will always be a Starbucks in easy walking distance. But it's not the same multi-ethnic, diverse community."

County officials sent affordable housing advocates door-to-door in the Overlook to inform residents about the conversion. They tried to tell some of them that under Virginia law they have the right to ask KSI for a few hundred dollars in relocation money. But language differences and distrust were barriers, housing advocates reported, and some families left without getting any money for their move.

"These people work two or three jobs, and they don't have the income to support homeownership," said Karen Serfis, executive director of Arlington Home Ownership Made Easier Inc., who has been advising residents.

Serfis noted that 225 children, most of them preteens, live at the Overlook. Nearly all of them will be moving. That means that enrollment will drop suddenly at nearby elementary schools.

The displaced families will have few options as competition intensifies for rentals that do not convert to condos, said Cheri Zeman, executive director of Community Solutions, an affordable housing advocate. Rents are rising faster in the area than they are nationally, and vacancy rates are lower.

"With all these apartment complexes converting all around us, it's a scary thing that's happening," Zeman said. "There are tens of thousands of residents who will never own a home, and apartment living is their only option. They don't have down payments. They don't have the credit history to step into homeownership."

David Orgel is buying his apartment in the Shirlington Overlook, but many of his neighbors cannot afford to do so.The Shirlington Overlook complex is being converted to condominiums.