See link in my answer yesterday... also...
For a list of supported nVidia CUDA cards go to the FAQ
First read http://forums.adobe.com/thread/773101
PPro Video FAQ http://www.video2brain.com/en/products-118.htm
Quadro cards compared http://forums.adobe.com/thread/910140
>Premiere Elements 10 - Is Mercury Engine
There is NO mention of the Mercury Engine... in fact, all it says is...
"Graphics card with latest updated drivers" with no mention of a brand or model
I think you confused the Premiere Pro specifications page with Premiere Elements
The PPro FAQ List http://forums.adobe.com/community/premiere/faq_list should have what you need