That motherboard is DDR2 based and the maximum CPU is the Athlon 64 X2. Boards like that need the ATX12V which is a 4-pin power connector to handle the CPU primarily. Some of the power will be provided to the slots but most of that comes from the 2x12 connector.
To use a modern video card will require a better PSU than what you have generally but there is a benefit to the modern PSU, it can be used with a new motherboard/CPU/RAM when you upgrade