Yep, digital switchover (or, more precicely, analogue switch off) will improve everyone's digital terrestrial reception.
The switchover (both transmitters and receivers) cannot be achieved overnight so, currently, we are going through a transition phase. This involves transmitting both analogue and digital signals at the same time while consumers buy and install their digital equipment. Unfortunately, all the TV broadcast spectrum is already used up so, in order not to cause any interference to the old analogue service, the new digital signals are broadcast at low power from only a few main transmitters. Once everyone is ready, one of the old analogue channels will be switched off and one of the new digital multiplexes moved into its place. This will have several effects. First, there will be a tremendous boost in power from the main transmitter. Second, all the relays that are tuned to that transmitter will automatically pick up the new digital signal and start re-broadcasting it. Once one multiplex has been switched over correctly then the others will follow.
More details about the whole switchover here:
http://www.digitaltelevision.gov.uk/...ect_report.pdf
Also note the thousands of Gigawatt hours per year of extra electricity this is all going to consume!