Hi well you did not list the model number of your dell so we cant really tell what it is. Also a 3 tb drive you just cant plug in and have it work on a xp system or a system without uefi bios. If you have no computer experiance you understand if you plug that drive in wrong it can blow you mother board and the drive then you will have nothing. Also once you have the drive changed all programs windows and drivers will all have to be reinstalled. Yes there are adapters to change the regular power plug to a sata one you would also need a sata cable to connect to the mother board. Before you open any pc you first unplug it then push the power button to drain any power left in the psu. I really feel you need a pc shop and you should have bought the drive from that same pc shop they would have put it in for less money then. Also saves you from being stuck with a 3tb drive that wont work in your system. Sorry but thats the truth.
