Least amount of hardware would be motherboard, CPU, RAM, and video card. For the love of Jiminy, leave the hard drive disconnected until you know the PSU is okay.
Firstly - my old motherboard is perfectly fine, it seems like my old duron was fried and the motherboard itself doesnt support the thoroughbread athlonXP. Im now using a duron 1.2ghz (looking forward to upgrade soon :/)
The new motherboard, I found out it's a 'returned product' after realising the previous owner is stupid enough to short-circuit the sound pin's with the jumper-top. This cause the mobo to become fried.
Anyway a big thank you to those who contributed in solving my problem