Just a quick note to say that usb installation of Backtrack5 on all HP G series will not work, the boot will hang and gives an error, the only workaround is installation via DVD. as sound will not work with root login , the solution is:
Go to System->Preferences -> Startup Applications

Make sure you're in the tab 'Startup programs'
-> Click on 'Add'

Name: Pulseaudio daemon
Comment: Start the sound daemon

Now logout, then login again


Hope this helps.