some 'found' tracks are as low as 128kb. but the only ones that I have kept at the bitrate is hard to find muysic that I love. and I dont play it on my top shelf rig. most of my music for:
portable rig 1 in my sig. iphone 3G->pico->SE530/W3 is 192-320kbs, but with the occasional annoying track I got from the itunes store before they started itunes plus and you just got what you were given, with no choice in the matter at all

for
portable rig 2 32gb CF modded 5.5G DIYMOD->piccolino blackgate LOD->Pico->SE530/W3 its 256kb/s+ with more lossless than rig 1. but still has a few old favourites that I rock out to on the bus or somewhere particularly noisy (the only way I can enjoy it.
the
transportable rig a second new 80gb 5.5g DIYMOD (still finishing styling

and reripping for this)->piccolino VCAp dock->piccolino silver bullet RCA 2 mini->pico->SE530/W3 that is going to have a 240gb dropped in as soon as they become widely available and has all the lossless I have, plus some 256+
so while I like to listen to 320+ I have been known to slum it with 128 if the right mood/location arrives.