Choosing motherboard(cpu)/videocard +PSU

Hello,
I currently have an old Acer computer (6 years old) and i want to replace some components:
-the motherboard with cpu; (not to pricy)
-video card for gaming; (budget $60)
-And maybe a new power supply if it's needed (budget $60)

I've got a FSP Group Inc. Power Supply with:
AC Input (220-240V-3,5A-50Hz)
DC Output (300W)

I want a fast computer and good enough to play cool games.
I'm not familiar with computers. Any advice would be very appreciated! (Sorry for my bad english)