Need new processor + vid card = get new comp?

Would I be better off getting a whole new comp, or just buying a new processor and vid card?

Also, would I need to buy a new motherboard?

>>9
If you got it in '03 the only thing that's likely to be outdated is the video card.
But still, "whole new computer" doesn't answer the question. Do you, for example, consider a monitor to be part of that? Because that's a significant cost that most intelligent people wouldn't consider to be part of the computer itself.