Naturally realtors are going to tell you to buy. There is that $8000 credit people want. Go to the REAL financial people or watch their tv programs who will ALL tell you that if you plan on staying in your home 5 years or more, then you should buy. If you plan on staying LESS than 5 years, then you rent. I am not going to send my address to get you as a customer! Go to Suze Ormon, Howard Clark, and Dave Ramsey. They have been in this business for many years. They have websites. None will steer you wrong. I know moving with taking care of a relative and a baby is hard to move, but if you aren't going to stay, don't get stuck with a house with what it needs and then worry how are you going to sale it. This is no time to think of investment. Many realtors and known "flippers" can't get out of many homes they bought with the price they put into them. They rent these houses out at a high price where they know people work for the federal government (military bases and such) and college students who share the price of a $1000-3000 rental. There are more houses going to foreclosures: those who refinanced and then lost jobs or can't afford the new mortgage and the other houses coming to foreclosure from ARM's re-setting. I just seen you wrote this Sept. 30, 2007. I hope you didn't buy!
Even if the market continues to slide, you will have had the tax advantage of home ownership during that 2 year period. You can then use any equity you have in your DC property and purchase a home in another location that has gone through the same economic conditions.