I have a VAIO SZ that came with the Toshiba stack, I removed it and installed a Widcomm 5 stack. I can't sync over BT (only works with MS stack) BUT dial-up networking works perfectly, so does transferring files - even allows the PC to be used as an audio gateway (headset) for the BB.
Not being able to sync over BT is a fair price to pay for the excellent functions available with the Widcomm BT stack.
Check the Sony forum at Notebook and Laptop Reviews
on the detailed instructions how to uinstall Toshiba and install Widcomm.