I wholeheartedly agree with you. I have a digital converter permanently tuned to Radio 7, plugged into my PC, using Total Recorder to capture.
My favourite must be The Navy Lark, especially the first series with Denis Price as the Number One. It brings back memories (albeit vague!) of listening to the first broadcasts in the late '50s - on a battery operated valve wireless set. My father would be roaring with laughter at some things I did not (yet) understand. To hear them again, in such quality, is wonderful.
This is closely followed by I'm Sorry I'll Read That Again, and several other marvellous '60s and '70s radio comedies. I exclude The Clitheroe Kid from the list, as this was a show I never liked, either as a child or as I grew up.
I've also build up a large collection of Radio Plays from the '40s onward that have been uploaded to the various newsgroups. I think that I must have all the American Basil Rathbone Sherlock Holmes, for example.
Grand day for a little nostalgia.