Well, I took the plunge and flash mine with HP BB BIOS 5.06 that was recently released and installation of Vista 32-bit was fine.
However, when I tried to install the BB Nvidia driver, it reported error msg that my system does not meet the (hardware?) requirement. BB Networking driver installed without problem but the same error msg was reported on the BB drivers for Soundmax, SATA etc. One finding was that after I installed the Soundmax driver from Asus SE, I did manage to install the BB Soundmax driver over it but not for the BB SATA and Nvidia drivers.
After googling for weeks, it was also reported that you need the BB ATI or Nvidia drivers and the trick to use newer ATI gfx is to update only the driver but leave the CCC untouched. However, I need to be able to install the BB gfx drivers in the first place!
Look forward to some good news on getting their DIY BB running or confirmation that I should give up trying due to some unknown hardware restriction that HP BB has that prevent this. BTW I am using 9600GT SLI and not sure if I need to use 8800GTX or Ultra as in the original setup and that the error msg is telling me that the new 9600GT SLI is not supported.
Regards,
Richard@Singapore