Yes, AM3 cpu's are backwards compatible with socket AM2, but in actual practice, finding a motherboard with bios update needed to make this happen is VERY rare. Rarer still with royalty OEM's like dell.
How your cpu was fried is also a worthwhile question to explore. It might have contributed to the problem.
Static discharge. I'm on a carpet right now and I never thought to ground out the electricity when I started to fix this computer. Really just needed a new OS. Question is answered anyways if I can't do the cpu change I'll just return it simple as that.