Use of the PC is?
Since as far as i can tell, that MoBo PCI-E x16 slot is version 1.0.
So, even if you get modern(-ish) GPU, that would use PCI-E 3.0, the GPU will run 4x times slower than it is capable of, due to the limitation of PCI-E 1.0 on your MoBo.
Overall, i don't suggest spending any money for dedicated GPU for that PC. Instead, buy a new PC. Unless you get a GPU for free.