I suggest you keep them in at least 128 format, unless you have a pair of crappy 1inch speakers connected to your PC.. I have about 12-14GB of music on mine. If you need space, archive some of it on CDs, but personally I would only convert them to less than 128 for the phone.. Though I'm getting my 256MB SD soon and am looking fwd to forgetting all my conversion problems.
For SPV I used 72K stream and it turned out ok for SPV headphones.
I personally prefer music in 192K and 256K mp3's - you can definitely hear the quality difference even if you are musically deaf, like I am
.:: PocketMVP Skins :: Marcelo :: WinMedia :: Marcelo2 :: DeepcleanSP ::.
.:: Tweaks :: EarSaver :: iZip :: VoiceRec :: ASXCoder ::.