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.