I use winamp -- and it works fine from the HD. It works great using a USB NIC (Netgear 101a). It doesn't work so great using a proxim symphony wireless NIC (haven't tried it with a self-powered hub yet, but I will).
Also, pretty much all of my mp3s are 192kbps or less. Maybe yours are like 320?
If you're running winamp, also try ENDITALL (or do a CAD) and shut down everything running in the background except Explorer and SysTray -- THEN run winamp. It could be something running in the background effecting it.
You also might want to make sure you dont have any winamp plug-ins active.