you may want to check out these as well
http://www.radioreference.com/forums/forumdisplay.php?f=113
http://www.radioreference.com/forums/showthread.php?t=49961
also look in the new Federal Forum
there really aren't any digital freqs for Winchester or Frederick County that I know of. Clarke Co is supposed to go digital (I'll post what I found in the FCC license DB below). you should be able to receive Loudoun Co and Berkeley Co, WV while in Winchester.
Clarke Co. New
I put them as freqs for a P25 trunked system and along since I'm not sure how they are going to use them.
0151.1675
0154.0475
0155.6925
0155.7225
0155.7825
0154.4825
0151.0775
0155.7525