|"I even went as far as cleaning the heatsink and metal processor cap considerably and reinstalling the thermal grease !!!!"|
You make it sound like you went above & beyond what was required of you. Whenever you swap a CPU, the heatsink & CPU must be thoroughly cleaned & new paste applied. In the case of your dual core Pentium, you should have a applied a thin horizontal line of paste across the center of the CPU, no spreading of the paste is necessary.
But as Fingers stated, you can't swap a HDD with XP already preinstalled. The installation is tied to the original hardware & will not work with the new board. Plus being that it's an SATA HDD, reinstalling XP will be a bit tricky. I doubt the Dell disc will work so hopefully you have a retail XP disc to work with.