The only thing that may improve with a new graphics car is the OpenGL preview. A newer card may be able to handle more items in the preview and show you better textures in the preview. I'm saying may on purpose, since it's not always the case, but in your case it will be.

 

The FX5200 is quite old and isn't capable of handling all the newer OpenGL features. If you upgrade to a newer card you will see a good improvement in the quality of the OpenGL preview in Poser. Also the preview update speed will be improved and a newer card with more memory will also be able to correctly show all items in more complex scenes.

 

Otherwise, rendering and such you will not see any improvement at all.

Artwork and 3DToons items, create the perfect place for you toon and other figures!

http://www.renderosity.com/mod/bcs/index.php?vendor=23722

Due to the childish TOS changes, I'm not allowed to link to my other products outside of Rendo anymore :(

Food for thought.....
https://www.youtube.com/watch?v=pYZw0dfLmLk