How much power do i have left?

[aivis1322]

Hello.
Today i had physics lesson in school. We learned about electricity.
So i thinked about my pc for a minute. How much my pc is eating power and how far i can push it.
I have 350W PSU
Intel Celeron D 331
Ati radeon x300/x550/x1050 series GPU i guess 512mb or 128mb
Asrock 775dual-vsta MB
160GB 7200rpm HDD
I don't know brand but 1GBx1stick abd 512MBx1stick
No parts overclocked
So how much hardware can i put more? Or even my rig have enough power to handle it all? How much my CPU get power (voltage)? Can i overclock it without pushing voltage?
Anyone have any experience with overclocking Celeron D? (prescott celeron and is usually running 68° to 80° when playing games) and i am running Windows XP and sometimes Elive Linux (from USB stick)
I know this pc is outdated but soon i will need laptop for new school and after 8 days i will have Win 8.1 tablet. So it isn't that bad

 

[Killer MO]

You won't be able to put more. First of all the mobo socket is old so you need to buy a new mobo, cpu and ram. The psu is good if you don't want a dedicated graphics. Get 8 gb ram ddr4 a good mobo and i3 6100 that has an integrated graphics.