You killed your computer, that's what you did. What psu did you replace the burnt out one with?
Did you take out the cpu or ram? does the pc post before it shuts down?
AMD Athlon 64 3200+
512 MB 2700 (Soon to be 1gb PC 3200)
ATI Radeon 9500 Pro (Soon to be ATI Radeon AIW 9800 Pro)