If you have cable internet coming into your house, you may not need an antenna at all. Just run a coax cable right into your TV or into a tuner if your TV is not very new, do a channel scan and see what happens. Through some agreement with the FCC, cable companies are supposed to send at least your local network affiliates as unencrypted channels. If your cable company is oddly generous, they may send more channels unencrypted. You can check a list here
http://www.silicondust.com/support/channels/ to see how the channels should map to the new digital numbering scheme.
Anyone who's considering an antenna should check this first. YMMV though. A friend down in Baltimore said it worked for them for a while before one day they all just disappeared. Then again, they're not exactly tech savvy so who knows what really happened there.