If you are a "spare time computer mechanic": Disconnect everything connected to the motherboard (harddrive, floppy drive, pci-card)(!).
Don't remove the video card, you need it. (maybe it's an on-board video card?)
If you got one, try another video card.
Remove the memory.
Remove the CPU.
(Final?) Test (Everything removed except power cables and video card)
Don't remove any of those tiny wires connected to your motherboard, they are power/reset-connectors and probably usb-wiring. There's no point in removing them.
Finally: Do this only if you are sure you can put things back correctly and know how to discharge yourself and your computer.
Edited by vict0r, 07 January 2009 - 01:36 PM.