Getting radio into iTunes and onto an iPhone

[geoff.getiplayer_list at alphaworks.co.uk]

I'm trying to get BBC radio programmes into iTunes and onto my iPhone 
under Windows XP. Now that we can't get MP3s I'm a little confused...

While I understand I can use FFMPEG to convert into MP3s the AACs that 
are downloaded, from what I've gleaned from this list I'm not sure this 
is the best solution. As I understand it, converting from AAC to MP3 is 
transcoding which is lossy and time-consuming. Can someone explain to me 
what these AAC files are and why iTunes won't recognise them (it fails 
silently)? I get the impression iTunes should handle AAC but is this an 
issue of containers / codecs?

I tried the advice given in 
http://lists.infradead.org/pipermail/get_iplayer/2011-March/000928.html 
( mplayer -ao null -vo null -dumpaudio -dumpfile audio_file_fixed.aac 
original_audio_file.aac ) which turned a 43MB (120 minutes flashaaclow) 
AAC file into a 2.6MB AAC file. Given the size of the output file I was 
sceptical that this had worked but it seems to play and be complete, why 
did this shink the file so much? Was this remuxing or something else? 
iTunes still won't import the file so that doesn't seem to be a solution.

Any explanations of the issues here (mainly about AAC I think...) would 
be much appreciated!

Kind thanks