I have an older eMachines Desktop PC model EL1360G which has a 200 watt power supply. I would like to upgrade it to at least a 400 watt power supply. Does anyone have a suggestion as to where or what I should buy? I watched a few videos on youtube on how to do the replacement but how do I know all the plugs on the new unit are the same and will fit? Because if they don't, I'll be more confused than I already am.