with 138mb of memory... thats a weird ammount!!
anyhow that aside my personal fav is sony erricson walkman phones, i've had a w810i and my phone now is w910i, both have memory card slots and I have a 2gb card in my 910 which gives me enough space for about 40 full albums ripped at 128kbs (near CD quality) the supplied headphones are not great but I don't care as I use the music player mainly in my car and run it into the stereo, if i do need the headphones I use my old k750i ones which are far better.
Anything you may hear/read about the tinny sound from sony phones is down to the headphones, the audio quailty is fantastic if you put it through a decent headset or stereo.