bluesmirf baud rate setting

i am using arduino+bluesmirf

here is the situation

Arduino<->PC (using bluesmirf + USB bluetooth dongle) @ 115.2kbps Arduino->PC is fine, but other way Arduino gets garbled data

Arduino<->PC (using bluesmirf + USB bluetooth dongle) BELOW 115.2kbps no data transfer although bluesmirf led changes to green

Can anyone guide me how to make bluesmirf communicate at lower speed?

I am using Dell Laptop with windows XP.

Thanks