Your TV channels probably look crappy because they aren't HD. Do they fill up the screen or do you have black boxes? I'm going to guess they fill up the screen, so you are seeing everything stretched. That'* the major complaint with the flat screen TV'* is they look pretty crappy with standard television. What model TV is it? If it has the tuner (QAM I think?) inside you may not need an external antenna to get some channels.
Go over to www.avsforum.com
to get some advice. Go to the forum, the "HDTV Area" section, then the "Local HDTV Info and reception" section. Then look for a thread for your particular area and you can get some idea as to what services are the best in your area, and what antenna is the best to get the locals over the air.