Apparently, from the information I have found on the web, an Emachine is from the AGP-era of graphics evolution. That would indicate that a PCI-e card will not be compatible with the motherboard.
You could chage the motherboard, but then you're almost certainly going to have to change the CPU and RAM as well.
If you're ready to do all that, you might as well by a new PC.
Pascal.
I've got nothing to hide, and I'd very much like to keep that away from prying eyes.