The 200 series I am guessing you have an Xpress 200 series Radeon graphics card meaning you have PCI-Express so your choices are based on your budget really. You system supports all of the latest GPU's physically with the exception of your Case and PSU. (Case might not be big enough for certain GPU's and your PSU might die trying to power a good portion of them).
Now although I did say you have PCI-Express can you give us the actual model of your system or a link to it on the internet so we can check if you have a PCI-Express x16 slot or you could look inside your system and see if you have the slot. That and I want to make sure you have a Midsize case and not something that won't fit a normal sized card or if you need a Half-sized card or not.
(reference -> http://en.wikipedia.org/wiki/File:PCIExpress.jpg
The two larger ones in this picture)