My name is Matt, currently I'm in the DC area. I recently moved from the Baltimore area. I have a Schwinn MTB (lurked for a while to pick up that little gem). I don't really care what anybody thinks about schwinn. I beat the hell out of that thing, and it loves me anyways. I don't do off-road tracks competitively, and I'm usually by myself for it, so I have little-to-no incentive for getting anything 'better'.
However, after moving to this area, I'm finding that I'm doing less of the rough terrain stuff, and more paved trails and city riding.
One of the previous posters equated riding to crack cocaine . . . well, I don't know about that but I'm certainly hooked. Reading some of the other forums has really got me thinking about competitive riding.
Have you tried the trails around Wakefield Manor yet? (Annandale, beltway at Braddock Road)
Or Fountainhead Regional Park? (west end of Fairfax County on the Occaquan River.)
Or Two Creeks? (WO&D into Loudon County, at Goose Creek just before you enter Leesburg)