Your home is in a great location at Oak Manor, one of the very desirable area in Fairfax. Nice size at 2,200 sf, over 1/4 acre lot, top of the hill, next to open space, nestled in the woods with gorgeous views of Mt. Tam. Private and updated with nice deck in the backyard.
This is just from my research, not knowiing the inside of your house, it's difficult to tell. There a recent listing on 441 OaK Manor which is about 200 sf less than your home, not as nice area, and the home actually consists of a smaller main house and a downstairs rental unit. The property is listed at $829,000. However, the property can not compare to yours.
On the other hand, 1 Snowden sold for $1,755,000 in 10/2007; but that's also a totally different property, built in 1982, 2455, sf, but completed remodeled in 2001 with a tax record at 2455sf (but owner claimed 3164 sf) Craftman style home with 2.71 acres of lot. So, that's quite different from yours also.
The other home that's similar to your is on Gregory, sold for $935,000 in 11/06, bit ealirer than we like to use as comp since it's sold before the housing market problems. However, the location is not as nice as yours, and the house is a little smaller and at not as nice setting as yours. .
Although a lot of homes are coming down in value, Oak Manor homes are very desirable and as you can see, not many are on the market. Again, like other Realtor said, without seeing your home, it's very difficult to say; but I would venture to guess it at mid to high $900s.