some stations had to change towers to put their digital transmitters on teh air due to tower loading. manyh of these WILL go back to the original towers after the switch and things will be basically teh same coveragewise. others will not go back and thus the new area may be different than it used to be.

another thing is many analog VHF stations are using UHF right now for their digital. but after the switch they will go back to VHF. if you wasted your money on a powered HD ready UHF antenna, you may be screwed. i keep telling everyone tha tyou don't have to buy anyting but the convertor, your existing antennas will work in 95% of cases.

as far as more interference, in MY case it is actually less and better signal. i have never been able to pick up the local CBS nor PBS stations. with digital i cna get both, so i went from 1 ABC station to 7 digital channels. if i ever get off my butt and put up my antenna outside i should be able to pick up a few more channels easily.

Here's a link to the expected digital coverage area compared to the present analog coverage for each TV market.

Here is a link that might be useful: Coverage Maps of Digital TV Stations