Are you asking if upgrading one or more components of either system will improve performance without having to build from scratch? Because, I would say that with the first one, everything is the bottleneck, and with the second, the processor and card are the bottleneck.
With the first one, it looks like the motherboard does not support PCI-E? If this is the case, any relatively newer card is out of reach. On the second system, you might be able to upgrade the graphics to a low-end GTX (possibly), and then the processor would be the bottleneck.
Are you wanting to play newer games, or what are you wanting to do?
What power supply do you have?