To update the Bios you will have to go to the website fo the motherbaord and know the EXACT model. You will be able to download the falsh tool to update the Bios.
With it being a Hp pavalion 844 you may need to goto there webiste and check for Bios updates from there.
Also doing a Bios flash is risky if you do not know what you are doing.
It is staight forward if you do it correct. But if anything is done to interupt the flash then it will kill your mobo.
Just make sure the elctrics in the home do not go out while doing the flash.
Check the cables yet again, also make sure the jumpers are set corect in the drives.
If the drive does not open are you seeing power to the drive?
Also upgrading your friends computer is to XP? does his computer fit the specs for Xp is it modern upto date hardware(ish)
You will need to tell us exactly what message you are getting on the screen.